Heat pump

In this study, an energy management model for electric vehicles including the entire vehicle such as the cabin, electric motors, battery, and the heating-cooling system was prepared. The heating and cooling processes for electric vehicles were run according to the internationally recognized driving cycles as well as at constant speeds to investigate them under different ambient conditions. The heating-cooling processes were managed in line with the cabin temperature target determined by considering the comfort conditions. The energy consumption of each of the system elements and the system in the heating-cooling process in electric vehicles was analyzed. Under different operating conditions, the variation of cabin temperature with time, instantaneous power, and cumulative energy consumption was calculated. The effect of heating and cooling processes on energy consumption, charging rate, and range were analyzed and interpreted. The results showed that the heating-cooling system for the heating process consumed more energy when the ambient temperature decreased, and the charge consumption ratio as well as the range deformation rate increased to about 30% when the ambient temperature was-10 • C. Similarly, the heating-cooling system for the cooling process consumed more energy when the ambient temperature increased, and the charge consumption ratio as well as the range deformation rate reached up to 40% when the ambient temperature was 40 • C. When the outdoor conditions were close to the thermal comfort temperature of 23 • C inside the cabin, the total energy consumption and the range deformation rates were reduced to less than 10%.

This study presents a comprehensive exergy-based thermodynamic analysis of a standalone liquid air energy storage (LAES) system integrated with internal thermal storage and an Organic Rankine Cycle (ORC) for sustainable large-scale energy storage applications. Unlike conventional studies, this work focuses on providing a scalable design framework by quantifying storage fluid requirements on a per-unit-mass-flow and per-MWh-capacity basis, enabling the results to be generalized for various power outputs and storage capacities. The proposed system configurations with two-and three-stage compression were compared in terms of liquid yield, round-trip efficiency (RTE), exergy efficiency, and storage fluid requirements. Results indicate that the optimal operating pressures are 190 bar for charging and 130 bar for discharging. At 200 bar charging pressure, the liquid yield increases from 0.51 (at 60 bar) to 0.86, while the maximum RTE reaches 62% in the base case and 68% with ORC integration. Incorporating ORC enhances the RTE by approximately 6-7% compared with conventional configurations through improved low-grade waste heat recovery and energy utilization. The two-stage compression configuration with ORC demonstrates the best thermodynamic performance, providing higher exergy efficiency, greater net power output, and lower thermal storage requirements. Furthermore, the reduction in thermal storage fluid demand contributes to improved resource utilization and lower infrastructure requirements for large-scale deployment. Additional sensitivity analyses indicate that thermal losses significantly reduce system performance, whereas ambient temperature fluctuations within ±15 K have only a minor influence on round-trip efficiency and liquid yield due to compensating effects between charging and discharging processes. The findings of this study provide scalable design insights for LAES systems and demonstrate the potential of ORC-assisted LAES technology to support renewable energy integration, sustainable grid flexibility, and low-carbon energy infrastructure development.

The African continent is experiencing an unprecedented escalation in the frequency, duration, and intensity of severe heat waves. This manuscript examines the thermodynamic and atmospheric causes of this crisis, evaluates its catastrophic socioeconomic and ecological effects, and proposes a sustainable, above-ground mechanical solution. Building upon the framework established in our previous work, "Utilizing Carbon Dioxide for Grid Stability in Ghana as an Ethical and a Sustainable Alternative to Underground Storage," we reject traditional, high-risk sub-surface carbon sequestration. Instead, we advocate for a paradigm shift: intercepting excess industrial carbon dioxide (CO_2) and deploying it as a thermodynamic asset in above-ground supercritical CO_2 (sCO_2) power cycles and closed-loop grid batteries. By placing these energy storage storage installations adjacent to expanding renewable energy zones across Africa, we can simultaneously mitigate the root cause of global warming, stabilize fragile national grids, and provide the reliable cooling infrastructure necessary to survive an overheating climate.

The use of capillary heat exchangers with a large area means the lowest heat carrier temperature -typically less than 30 °C for heating. This determines the very efficient use of the installed heat pump due to an increase in the coefficient of performance (COP) with a decrease in the provided water temperature. The aim of the study was to find out whether renewable energy sources and radiant capillary heat exchangers increase energy efficiency. In order to achieve the maximum energy efficiency during the renovation of the existing apartment, a combination of two green approaches was used. One of them is the replacement of the existing high-temperature radiator heating system with radiant capillary mats. The same system is also used for cooling, which was not possible with the existing system. The necessary energy is provided from renewable aerothermal energy by installing a heat pump together with PV panels to ensure electricity consumption. The measurements were made in the apartment to determine the thermal transmission properties of all boundary structures and an air exchange rate using long-term monitoring. Experimental data were used to create the heat balance, to estimate the heating and cooling powers, as well as the seasonal energy needs. The amount of capillary heat exchangers and the size of the heat pump were chosen accordingly. The very first energy consumption data allow concluding that the planned improvement of the energy efficiency has been successfully achieved by using technology combination described without improvement of the thermal properties.

Water heating and dehumidification are major energy consumers in buildings. The novel semi-open absorption heat pump design utilizes the heat of absorption from the dehumidification of space for water heating. The architecture of the system consists of (1) a plate and frame membrane-based absorber, (2) a membrane-based desorber and condenser unit, (3) heat exchangers, (4) ionic liquid, and (5) a 189.3 L (50-gal) water tank. The membrane-based absorber enables heat and mass transfer between three streams: moist air, ionic liquid, and the heat transfer fluid. The heat of vapor absorption elevates the ionic liquid temperature and, in turn, heats the heat transfer fluid. In the desorber unit, the diluted ionic liquid after absorption is heated to above 150℃ and reconcentrated. The heat of condensation from the condensation of water vapor in the condenser is utilized for water heating. The dehumidification performance of the absorber directly affects the COP and heating capacity of the system. Understanding the absorber's performance at various operating conditions would allow one to optimize and design a better performing absorber. In this study, the absorber's water heating capacity and performance are evaluated for varying operating conditions. A maximum COP of 1.25 while water heating water from 18.6 to 60.2°C was achieved at a capacity of 1,010 Watts and an airflow rate of 47.19 L/s. Increasing the desorber oil mass flowrate had negligible effect on the COP. The average mass transfer resistance of the porous membrane absorber was 1.164 *10 7 m/s.

────────────────────────────────────────── This paper examines the efficacy of various residential retrofitting strategies aimed at enhancing energy efficiency within the home and garden sector. As residential energy consumption accounts for a significant portion of global carbon emissions, identifying the fastest and most impactful upgrades is critical for sustainable development. Through a comprehensive review of current technologies-including smart thermostatic controls, high-performance insulation, and low-flow water fixtures-this study evaluates the intersection of upfront capital investment, annual utility savings, and property valuation increases. Preliminary research indicates that while large-scale solar arrays provide substantial long-term independence from grid volatility, modular interventions like LED transitions and smart temperature management offer the most immediate returns on investment for the average homeowner. This analysis provides a structured framework for prioritizing eco-friendly upgrades based on empirical performance data and consumer behavioral trends.

Efficient heat transfer is key in achieving safe and energy-efficient industrial pasteurization process. This study evaluates the thermal performance of a heated 500 liter double-jacketed mild steel pasteurization vessel using thermal oil filled industrial pressure burners. This process involved the experimental investigation of two burner configurations under controlled laboratory conditions, with both water (500 L) and thermal oil (25L) temperature profiles closely monitored at 30-60 minutes intervals. Initially, the system operated a three burner configuration (baseline), showing slow heating rate, limited thermal efficiency, and extended pasteurization time; requiring 300 minutes to achieve a water temperature of 81°C, while oil temperature peaked at 71°C. To improve performance, a fourth burner configuration (modified) was introduced, and the system's heating profile reassessed. In contrast, the four-burner configuration achieved 82°C water temperature in 210 minutes, while the oil temperature stabilized around 99-100°C, representing approximately a 30-35% reduction in processing time and a near 40% increase in maximum oil temperature. The findings indicate that increasing the number of burners significantly enhances conductive heat transfer and thermal responsiveness, reduces processing time, and stabilizes the system for continuous pasteurization cycles. This study evaluates pasteurization systems by demonstrating a practical approach to increasing thermal efficiency through burner configuration adjustments. The outcomes provide a benchmark for industrial scale doublejacketed pasteurization equipment design, enabling faster processing, lower energy consumption, and improved operational reliability. Future work will focus on integrating remote monitoring and automated control for High Temperature Short-Time (HTST) pasteurization to further improve process safety, efficiency, and scalability.

This paper deals with: i) modeling of a ground water heat pump and a thermally stratified fluid storage tank in a building energy simulation software ii) validation of the models using measurements taken in a real building and by comparison with experimental results from existing literature and iii) application of the models in a simulation based parametric study of the thermal and energy performance of combined low temperature space heating and domestic hot water system in a typical residential building confirming to current European standards.

In recent years, global crises, geopolitical conflicts, and climate change have brought food security to the forefront of the macroeconomic agenda and necessitated a transition to technology-intensive agricultural systems. This study presents a comprehensive techno-economic evaluation of soilless greenhouse clusters, drawing on a nationwide empirical case study of the Geothermal GOAZ (Greenhouse Organized Agricultural Zone) model in Turkiye. The analysis examines in detail the cost-reducing effect of centralized geothermal heating, its capacity to make agricultural production independent of fossil-fuel price shocks, and the stability of market supply dynamics in the context of the Cobweb Theorem. Additionally, this framework evaluates the integration of industrial symbiosis, Public-Private Partnership (PPP) governance, and the structural alignment between the EU Green Deal and the Carbon Border Adjustment Mechanism (CBAM). Statistical regression models empirically demonstrate the project’s high financial predictability and confirm that spatial clustering meticulously optimizes capital expenditures (CAPEX) through economies of scale. The study also highlights the model’s strong Environmental, Social, and Governance (ESG) performance, particularly in generating zero-emission carbon credits and promoting rural employment that supports gender equality. In conclusion, the Geothermal GOAZ model offers a mathematically validated, financially reliable, and scalable framework for sustainable agriculture. Furthermore, by integrating shallow geothermal heat pump technologies into the model, this central clustering model becomes globally applicable across all geographic and climatic conditions, including regions without hydrothermal resources.

Keywords: geothermal greenhouse, Geothermal GOAZ (Greenhouse Organized Agricultural Zone), agro-industrial clustering, Public-Private Partnership (PPP), ESG metrics, industrial symbiosis, carbon credit, climate-smart agriculture

The paper presents the study conducted to determine the impact of HVAC geothermal systems with heat pumps units on the ground and groundwater. Due its very complexity the HVAC geothermal system with heat pumps units that equips the ELI-NP research infrastructure could be a suitable tool to determining the long-term impact of shallow geothermal systems on the environment. The system has been continuously operating and monitored for 5 years.

French buildings highly contribute to the total nat ional energy consumption. In order to inflect the increasing tendency, significa nt efforts have been encouraged by public institutions. Accordingly, the GENHEPI concept, her eunder described, aims at methodically investigate retrofit operations to ensure an effect ive renovation of existing buildings. Its first phase consists in preparing and elaborating project s development by a global energy approach. Modelling and sensitivity studies of vari ous technical solutions permit this analysis. Then, an incremental improvement of perfo rmances is allowed by monitoring and interpretation of data obtained on each project. A multi competent team is gathered around the projects: researchers, architects, engineering offices, firms, banks and public institutions. Working together stimulates creativity which proves efficient on the currently carried out actions. The main objectives are focused on a reduc ed consumption of primary energy and ...

The transition toward climate-neutral cities requires large-scale building retrofits combined with collective renewable self-consumption. This study assesses the energy performance of en-SOLEX, a modular solar exoskeleton retrofit system, applied to a social housing district in Bari (Italy). The system transforms energy-intensive buildings into net-positive producers while increasing self-consumed electricity, improving the feasibility of Renewable Energy Communities (RECs), particularly in social housing contexts where energy sharing can reduce energy poverty. When integrated within a REC, en-SOLEX significantly enhances collective selfconsumption and mitigates increased demand from electrification. The selfconsumption index (SCI) rises from 65% in a rooftop PV scenario to 74-91% with en-SOLEX, reaching up to 98% under electrified conditions. The self-sufficiency index (SSI) also improves, achieving up to 43% in nonelectrified cases and remaining positive under full electrification. Compared to diffuse rooftop PV, concentrating generation on selected buildings reduces structural constraints, minimizes retrofit interventions, and simplifies decision-making, key barriers in social housing RECs. Overall, the study shows that combining deep retrofits, façade-integrated PV and REC-based energy sharing provides a scalable and inclusive approach to achieving Positive Energy Districts that are aligned with EU decarbonisation targets.

Water dispensers in hot climates often suffer from thermal stratification, which impairs cooling efficiency, increases energy consumption, and compromises user comfort. This study presents a novel comparative experimental evaluation of two active mixing strategies (mechanical impeller stirring and microbubble injection) to mitigate stratification and enhance energy performance in a 36 L vapor-compression water dispenser under extreme ambient conditions (up to 47 • C). The experimental design involved testing both strategies in steadystate and dynamic (12-hour simulated institutional usage) scenarios, using temperature sensors, power meters, and refrigerant cycle monitoring. Unlike prior studies focused on modeling or moderate climates, this work offers real-world performance insights under harsh summer conditions. Results showed that both strategies effectively suppressed thermal stratification, reducing vertical temperature gradients from 19 • C to < 1 • C. Cooling time to reach 10 • C decreased by 49 % with impeller mixing and 45 % with bubbles. Peak coefficient of performance (COP) improved from 2.90 to 3.23, and total energy consumption dropped by 20.6 %. While impellers delivered faster response, bubble injection achieved higher energy efficiency per watt. Economic analysis yielded payback periods of 9-18 months. Scaled adoption could reduce electricity use by 73 MWh and avoid 54 tonnes of CO 2 emissions annually per 1,000 units. These findings demonstrate the practical and environmental benefits of active mixing retrofits, contributing a robust experimental benchmark for advancing energy-efficient watercooling technologies in extreme climates.

In this study, combine operation of air source heat pump and vacuum tube solar collector system was experimentally observed. Contribution of heat pump system on solar collector system performance was determined. Solar collector experimentation setup was constructed with 30 lt water storage tank and 4 items vacuum tube. Heat pump condenser which is in the form of pipe coil was placed into the water storage tank. System evaporatör is fan assisted aluminium fin and 2400 W capacities. Heat pump compressor is 745 W power. Temperature was controlled by 303-363 K range thermostat. During the experimentations solar radiation intensity, heating time and temperature of water was recorded. Experimentations were repeated
for three different operation conditions. In the first day, solar collector and heat pump system, the second day, only solar collector and on the third day, only heat pump system was operated and experimentation was completed. It is determined that, the system efficiency was enhanced about 5% according to the evaluations.

The utilization of ejectors in heat pump systems as compression components, alone or in combination with other equipment, have gained renewed interest as a thermally driven solution for low temperature heat recovery and upgrading and more efficient energy use. This paper summarizes the main findings and trends, in the area of heat driven ejector based machines using low boiling point working fluids. An overall view of such systems is provided by presenting the ejector principles of physics and the latest developments on ejector design, operation and modeling approaches. Aspects related to the analysis of the complex interacting phenomena taking place in these systems for high performance are highlighted. Conventional and improved ejector heat pump cycles of interest employing ejectors alone or boosted combinations are presented and discussed, and their potential applications are indicated. Finally, sample theoretical and experimental results obtained at CanmetENERGY on ejector operation and design are reported.

The effects of flow direction and thermal short-circuiting on the performance of coaxial ground heat exchangers are studied by finite-element simulations, performed through COMSOL Multiphysics 3.4 (©Comsol, Inc.). The real 2-D axisymmetric unsteady heat conduction and convection problem is considered. The distribution of the fluid bulk temperature in the inner circular tube is determined by means of the "weak boundary form" boundary condition available in COMSOL Multiphysics; the laminar convective heat transfer in the outer annular passage is simulated directly. Two Coaxial Ground Heat Exchangers (CGHEs) with the same length but different cross sections are examined; moreover, two values of the ground thermal conductivity, as well as two materials for the inner tube wall are considered. The results point out that the annulus-in flow direction (fluid inlet in the outer annular passage) is more efficient than the center-in flow direction (fluid inlet in the inner circular tube) and that the effect of shortcircuiting is not very important, if the annulus-in flow direction is employed. Indeed, with this inlet configuration the energy loss for thermal short-circuiting is less than 1% for time intervals longer than 1 hour.

Seebeck effect (thermo-emf ), thermal conductivity and electrical conductivity of social hornet cuticle were measured in a direction perpendicular to the cuticular surface. The obtained value of the Seebeck coefficient (S) was about 3 ± 0.5 mV K -1 and its sign corresponded to an n-type (electronic) conductivity. Hornet cuticle is shown to be a fairly good heat insulator, with recorded values of the heat conductivity as low as 0.1-0.2 W m -1 K -1 . The measured value of the electrical conductivity in the linear regime is σ = 8.5 × 10 -5 -1 cm -1 . The thermoelectric figure of merit is computed. Implications for possible exploitation as a natural thermoelectric heat pump are discussed.

The Stirling engine is deemed to play a role in the near future of power generation. However, there is a large performance difference between the real and ideal Stirling engine. The use of sinusoidal motion for both displacer and piston in current applications is one of the reasons for this difference as it limits heat transfer. This paper investigated the use of non-sinusoidal rise-dwell-fall-dwell (RDFD) motion on both displacer and piston to improve the performance of a real Stirling engine and compared it to the conventional sinusoidal motion crankshaft driven Stirling engine. A gamma configuration Stirling engine test rig with a data acquisition system was constructed for this investigation. Among the four flywheels with each specifically designed cam profile tested, one was with sinusoidal motion while the remaining three were non-sinusoidal for comparison. The use of non-sinusoidal RDFD cam with 135° displacer dwell improved more than 36% thermal efficiency over sinusoidal motion crankshaft Stirling engine.

Food waste across the supply chain accounts for approximately 30-40% of total global food production, thereby exacerbating hunger, increasing the burden on waste management systems, and causing significant environmental degradation. Although food scarcity remains critical in many regions, a substantial proportion of food losses occur in developing countries, primarily due to the absence of affordable and effective preservation technologies. Conventional drying methods are highly energy-intensive, largely because of inefficient control over heat, mass, and momentum transfer mechanisms. Consequently, improving sustainability in food drying processes is essential to reducing energy consumption as well as minimizing associated environmental and social impacts. In this context, sustainable food drying technologies utilizing renewable energy sources represent a promising solution, particularly for developing nations. The integration of thermal energy storage with heat pumpassisted drying systems has been shown to enhance both drying efficiency and product quality. Likewise, advanced hybrid drying configurations such as solar-assisted microwave drying and heat pump-microwave drying-offer reduced operational costs while preserving superior food quality. Furthermore, the role of resource availability and government incentive policies in promoting the adoption of renewable energy-based sustainable drying technologies is also discussed.

The take-up of heat pump technologies in the UK domestic sector has lagged far behind other countries in Europe and North America due primarily to the ready availability of cheap natural gas; this has led to the predominance of gas central heating systems in UK housing. However, with recent gas price volatility along with the depletion of the UK's natural gas reserves interest in heat pump technology, particularly Air source heat pumps (ASHPs) is growing as they have the potential to be a direct, low-carbon replacement for existing gas boiler systems. However, to-date there have been few detailed, simulation-based performance studies of ASHP systems. In this paper a robust, dynamic simulation model of an ASHP device is described. The ASHP model has been integrated into a whole-building model and used to analyse the performance of a retro-fit domestic ASHP heating system. The simulation results were then compared to field trial data.

A predictive load shifting controller has been developed and deployed in a low-carbon house near Glasgow, UK. The house features an under floor heating system, fed by an air-source heat pump. Based on forecast air temperatures and solar radiation levels, the controller firstly predicts the following day’s heating requirements to achieve thermal comfort; secondly, it runs the heat pump during off peak periods to deliver the required heat by pre-charging the under floor heating. Prior to its installation in the building, the controller’s operating characteristics were identified using a calibrated building simulation model. The performance of the controller in the house was monitored over four weeks in 2015. The monitored data indicated that the actual thermal performance of the predictive controller was better than that projected using simulation, with better levels of thermal comfort achieved. Indoor air temperatures were between 18 °C and 23 °C for around 87% of the time between 07...

The ability of UK housing with heat-pump-based heating systems to respond to requests for immediate changes to load was assessed using a bottom-up stock modelling approach. Detailed building simulation models of the most common types of UK housing were developed and their ability to respond to signals to drop or pick up load tested under two different operating strategies: on-demand heating and off-peak heating with supporting thermal storage. Both the thermal storage and heat pump capacity were sized prior to undertaking the responsive load simulations. The performance of each building was simulated over a calendar year, with the response to load variation signals constrained by thermal comfort requirements and hot water needs, which took priority. Without thermal storage and following a typical on-demand heating pattern, approximately 20% of heating systems could respond to a drop load or pick up load signal. Switching to an off-peak heating pattern with sized thermal storage resulted, firstly, in the entire operation of the heat pump could be shifted to off peak periods. Secondly, the overall ability to respond to a drop load request was almost unchanged, but typically over 80% of systems could respond to a pick up load signal. The aggregate response figures mask significant seasonal and intraday variations in response, with the ability to respond being limited during periods of low heating and hot water demand. The addition of thermal storage reduced this variability.

A predictive load shifting control system for a heat pump has been developed and installed in a low carbon test house located at the BRE Innovation Park, Motherwell, near Glasgow. The house features an exhaust-air source heat pump supplying an under floor heating system. The controller predicted the day-ahead space heating requirements for the house, based on forecast air temperatures and solar radiation levels and then automatically set the heat pump's start and stop times for the following day. The heat pump's operation was restricted where possible to off-peak electricity tariff periods (00:00-07:00). The controller's operating parameters were pre-set using a calibrated building simulation model. After installation, the controller's performance was monitored during September 2015 and analysis of test data showed that the predictive control maintained indoor air temperatures between 18-23 o C for around 87% of notional occupied hours between 07:00-22:00; this was better than predicted by simulation. However, the energy performance of the heat pump was extremely poor as it did not function well under intermittent load-shifting operation, with the majority of the heat was delivered primarily by an auxiliary immersion coil rather than the heat pump itself. The paper concludes with suggestions for refinements to the controller and further work.

A predictive load shifting control system for a heat pump has been developed and installed in a low carbon test house located at the BRE Innovation Park, Motherwell, near Glasgow. The house features an exhaust-air source heat pump supplying an under floor heating system. The controller predicted the day-ahead space heating requirements for the house, based on forecast air temperatures and solar radiation levels and then automatically set the heat pump’s start and stop times for the following day. The heat pump’s operation was restricted where possible to off-peak electricity tariff periods (00:00-07:00). The controller’s operating parameters were pre-set using a calibrated building simulation model. After installation, the controller’s performance was monitored during September 2015 and analysis of test data showed that the predictive control maintained indoor air temperatures between 18-23 o C for around 87% of notional occupied hours between 07:00-22:00; this was better than predi...

Using a simulation-based approach, this work analyses the impact that different energy unit sizing strategies and control methodologies will have on the capital and running costs of an air source heat pump (ASHP) system installed in a refurbished dwelling. A total of 3 different system operational strategies were investigated and the cumulative cash flow over a period of 10 years (including initial investment) was utilized to compare the systems from an economic perspective. Additionally, in selected cases, the cycling of the heat pump was calculated in order to estimate the likely lifespan of an installation. The building and heat pump systems were simulated using the TRNSYS energy system modelling software. The results revealed the sensitivity of the system's costs and life-span to its control and operation. For example, operating the system as a direct gas boiler replacement resulted in capital costs above £10,000 and the unit's life span reduced to almost half in comparison to more favourable operational strategies. The results highlight the fact that the successful technical and financial performance of heat pumps within the UK's residential market will depend on designers', installers' and end-users' awareness regarding optimal operational strategies for the technology.

This study presents a comprehensive evaluation of the elastocaloric effect in a Cu 68.6 Zn 14.8 Al 16.6 shape-memory alloy single crystal, analyzing its thermodynamic response across a broad spectrum of strain rates (3.4 × 10-4 to 0.35 s-1) and testing temperatures. Direct measurements demonstrate that the adiabatic temperature change saturates at a strain rate of 0.15 s-1 , reaching a maximum of 9.2 K. Crucially, owing to the ultra-low baseline hysteresis of the single crystal, this thermal response is highly symmetrical during both the exothermic loading and endothermic cooling phases, corresponding to a transformation entropy change of 24.9 J kg-1 K-1. Uniquely, this work systematically addresses the dynamic evolution of mechanical dissipation; we demonstrate that although the unrecoverable work initially increases by up to 300% before saturating under near-adiabatic conditions, the concurrent enhancement in cooling capacity heavily outweighs this penalty, resulting in a net increase in the material coefficient of performance. Coupled with an outstanding elastocaloric responsivity of ∼ 77 K GPa-1 , these findings highlight the exceptional efficiency of Cu-Zn-Al single crystals and establish dynamic strain rate optimization as a key engineering strategy for high-frequency solid-state cooling devices.

Thermal refurbishment of buildings results in certain energy, financial, and environmental effects. Such investments are financially supported in Poland after meeting the legally defined conditions of thermal protection and energy consumption. This paper presents a complex thermal modernization of a school building, performed by following Polish regulations. A detailed description of the studied object was given, and the calculation procedure was described. Then an optimal variant of an investment and an ex-post analysis were described. Simple payback time (SPBT) of modernization measures was from 15.8 years (insulation of the ceiling under the unheated attic) to 87 years for insulation of the wooden external wall, with 35.6 years for the whole project, which is shorter than the predicted lifespan of the whole building (50–70 years). Annual calculated heating demand decreased from 464.78 to 168.73 GJ, resulting in the primary energy consumption indicator (EP) of 484.44 and 129.46 kW...

Heat recovery from ventilation air is proven technology resulting in significant energy savings in modern buildings. The article presents an energy analysis of an air handling unit with a cross-flow heat exchanger in an office building in Poland. Measurements were taken during one year of operation, from 1 August 15 to 31 July 16, covering both heating and cooling periods. Calculated annual temperature efficiency of heat and cold recovery amounted to 65.2% and 64.6%, respectively, compared to the value of 59.5% quoted by the manufacturer. Monthly efficiency of heat recovery was from 37.6% in August to 68.7% in November, with 63.9% on average compared to 59.5% declared by the manufacturer. Cold recovery was from 63.3% in April to 72.8% in September, with 68.1% annually. Calculated recovered heat and cold amounted 25.6 MWh and 0.26 MWh, respectively. Net energy savings varied from −0.46 kWh/m2 in August, when consumption by fans exceeded savings, to 5.60 kWh/m2 in January.

This paper presents a hybrid heating system of a school building with a heat pump and a gas boiler, which replaced an old coal-gas system. The description of the test object, the concept of heating system and its construction, commissioning, selection of electricity tariff to supply the heat pump and auxiliary equipment, control system, economic effects of investments carried out and further research plans are also presented. It was also determined the energy efficiency of the heat pump by means of COP and SPF factors. The results obtained indicate the correctness of assumed solutions.

Excessive energy consumption in the building of our interest proves that it necessitates modernization. Based on the Thermal Modernization Act [5], the necessary works could be possible due to the financial support, called &quot;thermomodernization premium&quot;, from the Thermomodernization Fund. During complex thermal modernization of the school building in Gródek nad Dunajcem (southern Poland), an old heating system was replaced with a new one whose operation being based on renewable sources of energy. Its design is described in [8]. This article presents the analysis of three-year (2004-2006) period of this system operation and its cost-effectiveness.

This paper presents a hybrid heating system of a school building with a heat pump and a gas boiler, which replaced an old coal-gas system. The description of the test object, the concept of heating system and its construction, commissioning, selection of electricity tariff to supply the heat pump and auxiliary equipment, control system, economic effects of investments carried out and further research plans are also presented. It was also determined the energy efficiency of the heat pump by means of COP and SPF factors. The results obtained indicate the correctness of assumed solutions.

The objective is to provide a technical and economic assessment of residential exhaust-air heat pumps for water heating with option for space heating. Compact one-cabinet heat-pump units containing a hot water tank with refrigerant condenser, exhaust fan, refrigerant evaporator, refrigeration compressor and controls have recently become available on the U.S. market. The emphasis is on U.S. applications with three representative climates: moderate (Northwest), cold (Midwest), and hot and humid (Southeast). The approach is to simulate detailed system performance for a full year of two typical houses equipped with the heat pump. TRNSYS, a transient building system simulation package, is used allowing detailed simulation of heat pump (and other HVAC equipment) operation including control action (on, off and hysteresis effects). Ventilation and energy performance of the heat-pump houses is compared to the same houses equipped with air-toair heat exchangers, and to naturally ventilated houses. Exhaust-air heat pumps are found to provide a nearly constant ventilation rate throughout the year as opposed to the natural ventilation rate that is found to be highly variable. Energy savings realized with the heat pumps are greater than those obtained with heat exchangers. However, heat-pump installation and maintenance costs are also higher than those for the heat exchanger resulting in broadly similar economics for the two systems. Both are cost competitive with natural ventilation in cold climates, and clearly uneconomical in hot and humid climates with present electric rate predictions. In the moderate climate of Portland, both heat pumps and heat exchangers are roughly economically neutral. Albeit neutral or slightly negative in economic terms, heat pumps offer the certainty of a constant ventilation rate throughout the year, a benefit for indoor air quality that is disregarded by the economic analysis.

In recent years, several emerging technologies in the domain of solid-state physics have been investigated as serious alternatives for future refrigeration, heat pumping, air conditioning, or even power generation applications. These technologies relate to what is called caloric energy conversion, i.e., barocalorics, electrocalorics, magnetocalorics, and elastocalorics. Of these technologies, the greatest progress has been observed in the domain of magnetic refrigeration. However, in the recent few years, significant research efforts have also been made in the field of electrocaloric and elastocaloric refrigeration. Many of these technologies suggest the possibility for improvements in energy efficiency, compactness, noise level, as well as a reduction in environmental impacts, so it seems very probable that they will start to fill particular market niches as a replacement for vaporcompression technology in the future.

U ovom radu se ispituju rezultati primene i postojanje sprege između dva uslova, koja su bitna pri kontrolisanju brojila u cilju mogućeg smanjenja vremena njegovog izvršavanja. Prema Pravilniku o brojilima aktivne električne energije klase tačnosti 0,2 S, zadat je prvi uslov za proširenu mernu nesigurnost mernog sistema za kontrolu brojila u odnosu na najveću dozvoljenu grešku brojila. Prvi cilj ovog rada je da se proveri da li je ovaj prvi uslov najkritičniji za cosφ=0,25 induktivno ili cosφ=0,5 kapacitivno, koji se zadaju na poseban zahtev korisnika brojila. U
gorepomenutom Pravilniku i Međunarodnoj preporuci OIML R 46-1/-2, zadat je drugi uslov koji će da bude analiziran, za relativnu razliku između energije na ispitnom izlazu i očitane energije na registru u odnosu na najveću dozvoljenu grešku brojila. Korišćeni su etalon klase tačnosti 0,02 i brojilo za indirektnu vezu klase tačnosti 0,2 S za aktivnu energiju. Drugi cilj
ovog rada je da se analizira da li, u smislu opravdanosti smanjenja vremena provere registra aktivne energije brojila, prvi uslov može da bude olakšavajući činilac. Dalje će da se razmotri da li ovaj drugi uslov može da se ublaži za brojila klase tačnosti 0,2 S, s obzirom na uobičajenu očekivanu ukupnu relativnu grešku koja se dobija pri proveri registra za aktivnu energiju i preciznost i tačnost korišćenih brojila te klase. / This paper examines the results of the application and the existence of a coupling between the two conditions, which are important when controlling the meter in order to possibly reduce its execution time. According to the Rulebook on meters of active electric energy of accuracy class 0.2 S, the first condition for the extended measurement uncertainty of the measuring system for controlling the meter in relation to the maximum permissible error of the meter is set. The first goal of this work is to check whether this first condition is the most critical for cosφ=0.25 inductive or cosφ=0.5 capacitive, which are set at the special request of the meter user. A standard of accuracy class 0.02 and an indirect connection meter of accuracy class 0.2 S for active energy were used. In the above-mentioned Rulebook and International Recommendation OIML R 46-1/-2, the second condition is set that will be analysed, for the relative difference between the energy at the test output and the energy read on the register in relation to the maximum permissible error of the meter. The second goal of this paper is to analyse whether, in terms of the justification of reducing the time of checking the meter's active energy register, the first condition can be a facilitating factor. It will further be considered whether this second condition can be relaxed for meters of accuracy class 0.2 S, considering the usual expected total relative error obtained when checking the register for active energy and the precision and accuracy of meters of that class used.

The article discusses the influence of the cold water temperature on the amount of energy consumed for the purposes of the DHW preparation in multi-family buildings. The article begins with a presentation of the DHW consumption readings from a multi-family building, recorded on a monthly basis during the period of 4 years. The readings constituted the base for calculating the demand for energy for the purposes of the DHW preparation. Subsequently, basing on the output water temperature readings from the water treatment plant, it was proved that the temperature of the mains water fluctuates throughout the year. The review of the available literature, as well as the measurements, confirmed that it is necessary to develop a new model of the cold water temperature that would take into account the type of intake in a water treatment plant. The final part of the article presents how the accepted assumptions about the temperature of the mains water influence the consumption of energy for t...

Heat pump systems for commercial building with variable refrigerant flow (VRF) are expanding a market due to high energy efficiency, lower maintenance cost and easy installation comparing with the conventional heat pump with the constant refrigerant flow. In general, heat pump systems degrade the energy efficiency in the extremely low temperature regions. In this study, VRF heat pump system with refrigerant heating is experimentally investigated to overcome the low heating performance in the extremely low temperature regions. VRF heat pump system with refrigerant heating is found out the sufficient heating performance in the -25 degree temperature condition comparing with the conventional heat pump system and is obtained more than 2,500 kPa high pressure in the evaporator at low temperature.

Heat pump systems for commercial building with variable refrigerant flow (VRF) are expanding a market due to high energy efficiency, lower maintenance cost and easy installation comparing with the conventional heat pump with the constant refrigerant flow. In general, heat pump systems degrade the energy efficiency in the extremely low temperature regions. In this study, VRF heat pump system with refrigerant heating is experimentally investigated to overcome the low heating performance in the extremely low temperature regions. VRF heat pump system with refrigerant heating is found out the sufficient heating performance in the -25 degree temperature condition comparing with the conventional heat pump system and is obtained more than 2,500 kPa high pressure in the evaporator at low temperature.

Cold Thermal Energy Storage (CTES) systems play a vital role in improving energy efficiency, reducing peak electrical demand, and supporting sustainable cooling technologies. This article presents a comprehensive experimental investigation of a Cold Thermal Energy Storage system. It explains the working principle, system components, experimental setup, methodology, performance parameters, results, discussion, advantages, limitations, and future scope. The study highlights how CTES systems can effectively store cooling energy during off-peak hours and utilize it during peak demand periods, thereby offering economic and environmental benefits.

When people choose an HVAC system, efficiency is one of the most important factors. It affects building approvals, electricity bills, system life, and overall performance. In the United States, federal regulations require manufacturers to publish standard efficiency ratings for their equipment. These ratings must follow the latest testing procedures set by the Department of Energy so that buyers can compare products fairly. Recent investigations have revealed that Islandaire HVAC systems are sold with efficiency information that does not meet federal requirements. Let's cover the details of this investigation.

Vertical farming requires a structurally sound and environmentally sustainable racking system; however, existing research largely neglects the evaluation of the structural safety of eco-friendly racking materials under various operational loads. This gap necessitates further rigorous mechanical performance assessments to ensure the long-term reliability of the system. This study aims to develop a vertical farming racking design with an adequate safety factor by examining its structural response to various load scenarios. A design construction methodology supported by SolidWorks simulations was used to evaluate stress distribution, strain behavior, and deformation patterns. Simulation results using SolidWorks software indicate that the maximum compressive stress at the loaded joint surface is 13.734 MPa, while the minimum stress is 1.149 MPa. The highest load occurs at the fourth (bottom) joint level due to pump-induced water pressure. The maximum strain recorded is 0.00491, with a minimum of 0.00041. The top shelf level exhibits a maximum displacement of 48.165 mm, while the minimum displacement is 0 mm. This shows that the material and shape of the frame that has been made are in the safe
category with a safety factor (sf) of 2.4. These findings indicate that the proposed rack design maintains structural integrity within safe limits and is suitable for application in vertical farming systems.

In this study, a concept of using a vapor compression heat pump for recovering and upgrading waste heat of an air-conditioner has been presented. R-290 has been selected due to its high efficiency and the environmental impact. R-290 heat pump at heating capacity 3 kW has been constructed to recover waste heat from the discharge refrigerant leaving compressor of R-134a air-conditioner at cooling capacity 1 TR. From the study results, it could be seen that the modified unit gives better EERAC when the cooling water does not over 43 oC. A set of simplified model has been developed to predict the system performance and the simulated results agree quite well with the measured data. Moreover, profile of hot water consumption in the department of children&#39;s hospital room, Maharaj Nakorn Chiang Mai Hospital is chosen to study. It was found that the hospital requires hot water is 0.815 m3/d at 50 oC temperature, one unit of R-290 heat pump is enough to generate hot water with the economi...

The freeze desalination cycle with seawater heat pump system is simulated and designed for the basic data for the design of freeze desalination system. The basic model of seawater heat pump system is refrigeration cycle and indirect freeze desalination method is used for seawater desalination. The cycle performance of seawater heat pump such as COP, compressor work, condensing capacity was analyzed and the desalination performance such as fresh water productivity and energy per unit fresh water productivity was compared with respect to the seawater temperature of condenser inlet and ice ratio in the evaporator. The compressor work and condensing capacity decreased with respect to the decrease of seawater inlet temperature. The energy per unit fresh water productivity in case of 8℃ seawater inlet temperature showed 28.9% lower than that of 20℃.

Ireland has a renewable heat sectoral target of 600,000 heat pumps by 2030 with currently just 44,000 installed. Such a high heat pump target will have a significant effect on electricity demand and on the management and operation of the electricity grid. Many studies rely on synthetic data to estimate the impact of the adoption of low carbon technologies. This paper explores residential electricity demand using an innovative dataset from a field trial of deeply retrofitted homes heated by air source heat pumps. We estimate the after diversity maximum demand during a period of extreme weather, heat pump comparing it to a typical winter day. We assess which statistical distributions best model the electricity demand per home heated by an air source. The after diversity max demand is 3.84 kW compared to 2.33 kW, while a Gamma distribution best models average coincident electricity demand for the homes.

The implementation of renewable energy systems (RESs) in the agricultural sector has significant potential to mitigate the negative effects of fossil fuel-based products on the global climate, reduce operational costs, and enhance crop production. However, the intermittent nature of RESs poses a major challenge to realizing these benefits. To address this, thermal energy storage (TES) and hybrid heat pump (HHP) systems are integrated with RESs to balance the mismatch between thermal energy production and demand. In pursuit of clean energy solutions in the agricultural sector, a 3942 m 2 greenhouse in Yeoju-si, South Korea, is equipped with 231 solar thermal (ST) collectors, 117 photovoltaic thermal (PVT) collectors, four HHPs, two ground-source heat pumps (GSHPs), a 28,500 m 3 borehole TES (BTES) unit, a 1040 m 3 tank TES (TTES) unit, and three short-term TES units with capacities of 150 m 3 , 30 m 3 , and 30 m 3. This study evaluates the long-term performance of the integrated hybrid renewable energy and thermal energy storage systems (HRETESSs) in meeting the greenhouse's heating and cooling demands. Results indicate that the annual system performance efficiencies range from 25.3% to 68.5% for ST collectors and 31.9% to 72.2% for PVT collectors. The coefficient of performance (COP) during the heating season is 3.3 for GSHPs, 2.5 for HHPs using BTES as a source, and 3.6 for HHPs using TTES as a source. During the cooling season, the COP ranges from 5.3 to 5.7 for GSHPs and 1.84 to 2.83 for ASHPs. Notably, the HRETESS supplied 3.4% of its total heating energy directly from solar energy, 89.3% indirectly via heat pump utilization, and 7.3% is provided by auxiliary heating. This study provides valuable insights into the integration of HRETESSs to maximize greenhouse energy efficiency and supports the development of sustainable agricultural energy solutions, contributing to reduced greenhouse gas emissions and operational costs.

The growing market penetration of heat pumps indicates the need for a performance test method which better reflects the dynamic behavior of heat pumps. In this contribution, we developed and implemented a dynamic test method for the evaluation of the seasonal performance of heat pumps by means of laboratory testing. Current standards force the heat pump control inactive by fixing the compressor speed. In contrast, during dynamic testing, the compressor runs unfixed while the heat pump is subjected to a temperature profile. The profile consists of the different outdoor temperatures of a typical heating season based on the average European climate and also includes temperature changes to reflect the dynamic behavior of the heat pump. The seasonal performance can be directly obtained from the measured heating energy and electricity consumption making subsequent data interpolation and recalculation with correction factors obsolete. The method delivers results with high precision and high reproducibility and could be an appropriate method for a fair rating of heat pumps.