Comparative performance analysis of a solar assisted heat pump for greenhouse heating in Tunisia
Abstract This work presents a comparative investigation of a heating system of a solar-assisted and a conventional heat pump using numerical and experimental studies. The heating system includes a tempered glass greenhouse connected with a water-to-water heat pump of a power of 10 kW, a solar collector, and a capillary tube mat as a heat distribution system. Furthermore, a comparative analysis of the system performance operating at the same condition with and without the solar energy was conducted. The system was optimized using the software TRNSYS to obtain the appropriate boundary conditions for the real system, and its best efficiency. The impact of climatic conditions on system performance is discussed. The Tunisian weather data were used to simulate heating systems by considering a 100 m2 glass greenhouse and 2 m2 as the collector area. The numerical simulations were validated by the experimental results. It was concluded that the proposed heating system could be adequate for greenhouse heating in winter. An area of a 2 m2 collector was found to match the heating load of a 10-kW power heat pump. The heat supplied by the solar collector at noon is between 1.5 and 4 kW in Tunisia and the heat pump with a power of 10 kW can supply the required amount of heating. The solar collector highly affects the performance of the water-water heat pump.