Theoretical model and experimental validation of a direct-expansion solar assisted heat pump for domestic hot water applications

Mathematical Thermal Modelling of a Direct-Expansion Solar-Assisted Heat Pump Using Multi-Objective Optimization Based on the Energy Demand

“…Table 5. Thermal capacity for the experimental setup by Moreno-Rodriguez [51]. As general observation of Tables 2-5, it is shown that τ C provides better results when analyzing accurate and specific data, and that with a shorter time step the level of accuracy of this parameter increases.…”

“…Figure 5 shows the experiment conducted by Moreno-Rodriguez [51] in Madrid during a year, a DXSAHP that worked 4 h per day. It was comprised by 2 to 8 bare flat-plate solar collectors installed in a parallel arrangement oriented to the south with an inclination of 40.4 • with refrigerant R134a circulating through them; a TSU with a capacity of 300 liters and a desired water outlet temperature of 51 • C. From the test, data from 5 characteristic days (maximum air temperature, maximum radiation, maximum wind speed and its combinations) was reported and is used to validate the model proposed in this paper.…”

Experimental investigation of a solar driven direct-expansion heat pump system employing the novel PV/micro-channels-evaporator modules

“…The analysis was carried out through a steady state mathematical model, and the results indicated that the heat pump COP was strongly influenced by ambient temperature and solar radiation, whereas it is nearly independent on solar field surface. Moreno-Rodríguez et al [5,18] carried out the theoretical model analysis and experimental validation of a direct-expansion solar assisted heat pump for domestic hot water applications. The results indicated that the theoretical COP could vary between 1.85 and 3.1, and the evaporation temperature varied between À8°C and 18°C.…”

“…Two types of SAHP, i.e., direct and indirect ones, are in existence [4] type, termed as the 'direct-expansion', makes use of the solar collector as the heat pump evaporator, thus enabling the direct evaporation of the refrigerant within the solar collector by receiving the striking solar radiation [5]. In a direct SAHP, if a photovoltaic (PV) module is fitted to the upper surface of the evaporator module, a PV/evaporator module is thus generated [6].…”

Experimental Study of a Novel Direct-Expansion Variable Frequency Finned Solar/Air-Assisted Heat Pump Water Heater

“…Chaturvedi et al [7] showed that the coefficient of performance (COP) of the system can be enhanced extensively by lowering the compressor frequency when the ambient temperatures are higher. Moreno-Rodríguez et al [8] showed that when the condenser water flow rate is lower than 0.114 kg/s, a higher COP can be obtained by reducing the compressor frequency. However, when the water flow rate is over 0.174 kg/s, lowing the compressor frequency will drastically lead to a lower COP.…”