Thermoacoustic heat pump utilizing medium/low-grade heat sources for domestic building heating

Thermoacoustic heat pumps are a promising heating technology that utilizes medium/low-grade heat to reduce reliance on electricity.This study proposes a single direct-coupled configuration for a thermoacoustic heat pump,aimed at minimizing system complexity and making it suitable for domestic applications.Numerical investiga-tions were conducted under typical household heating conditions,including performance analysis,exergy loss evaluation,and axial distribution of key parameters.Results show that the proposed thermoacoustic heat pump achieves a heating capacity of 5.7 kW and a coefficient of performance of 1.4,with a heating temperature of 300℃and a heat-sink temperature of 55℃.A comparison with existing absorption heat pumps reveals favor-able adaptability for large temperature lift applications.A case study conducted in Finland over an annual cycle analyzes the economic and environmental performance of the system,identifying two distinct modes based on the driving heat source:medium temperature(≥250℃)and low temperature(<250℃),both of which exhibit favorable heating performance.When the thermoacoustic heat pump is driven by waste heat,energy savings of 20.1 MWh/year,emission reductions of 4143 kgCO_(2)/year,and total environmental cost savings of 1629€/year are obtained.These results demonstrate the potential of the proposed thermoacoustic heat pump as a cost-effective and environmentally friendly option for domestic building heating using medium/low-grade heat sources.

First and Second Laws Analyses of a Closed Latent Heat Thermal Energy Storage System

First and Second Law analyses were conducted to evaluate the performance of a closed latent heat thermal energy storage (LHTES) system employing calcium chloride hexahydrate (CaCl2·6H2O). The First and the Second Laws of thermodynamics were applied to the system from viewpoint of energy and exergy analyses, respectively. The energy storage tank in the system is neither fully mixed nor fully stratified. It may be considered as semithermal stratified. Experimente that include both charging and discharging periods were performed on sunny winter days in 1996. The energy and exergy variations and the overall energy and exergy efficiencies of the closed LHTES system were calculated for the complete charging and discharging cycle of the selected fifteen clear-sky winter days. Mean energy and exergy efficiencies were found to be 55.20% and 34.83%, respectively.

A small-scale silica gel-water adsorption system for domestic air conditioning and water heating by the recovery of solar energy

A small-scale silica gel-water adsorption system with modular adsorber,which utilizes solar energy to achieve the cogeneration of domestic air conditioning and water heating effect,is proposed and investigated in this paper.A heat recovery process between two adsorbers and a mass recovery process between two evaporators are adopted to improve the overall cooling and heating performance.First,the adsorption system is tested under different modes(different mass recovery,heat recovery,and cogeneration time)to determine the optimal operating conditions.Then,the cogeneration performance of domestic cooling and water heating effect is studied at different heat transfer fluid temperatures.The results show that the optimal time for cogeneration,mass recovery,and heat recovery are 600 s,40 s,and 40 s,respectively.When the inlet temperature of hot water is around 85℃,the largest cooling power and heating power are 8.25 kW and 21.94 kW,respectively.Under the condition of cooling water temperature of 35℃,the obtained maximum COP,COP,and SCP of the system are 0.59,1.39,and 184.5 W/kg,respectively.