Thermal performance of a variable capacity direct expansion solar-assisted heat pump

• Published in: Energy conversion and management Vol. 39; no. 3; pp. 181 - 191
• Main Authors: Chaturvedi, S.K., Chen, D.T., Kheireddine, A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.1998; Elsevier
• Subjects: Applied sciences; Bare collectors; Capacity modulation; Devices using thermal energy; Direct expansion; Energy; Energy. Thermal use of fuels; Equipments, installations and applications; Exact sciences and technology; Heat pumps; Inverters; Natural energy; Solar energy; Solar heat pump; Solar thermal conversion; Capacity modulation; Bare collectors; Inverters; Solar heat pump; Direct expansion; Heat pump; Solar energy; Running; Hot water production; Control systems; Thermodynamic analysis; Experimental study; Performance
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/S0196-8904(96)00228-2

A variable capacity direct expansion solar-assisted heat pump system is developed and operated for domestic hot water application. The proposed system employs a bare solar collector which also acts as the system evaporator. A variable frequency drive modulates the compressor speed to maintain a proper matching between the heat pumping capacity of the compressor and the evaporative capacity of the collector under widely varying ambient conditions. Experimental results indicate that the coefficient of performance of the system can be improved significantly by lowering the compressor speed as ambient temperature rises from winter to summer months. Experimentally measured system COP H and water side heat capacity rate are also in good agreement with theoretical predictions.