UPGRADING OF SOLAR HEAT BY AN ABSORPTION HEAT TRANSFORMER ASSISTING WITH A VAPOR COMPRESSION HEAT PUMP

Abstract

In tropical area, even solar radiation level is rather high but diffuse solar radiation component is also very significant thus only solar flat-pate solar collector could be competitive with conventional energy for heat generation with a temperature not over 70 C o . For higher temperature applications, a technique to boost-up the temperature is needed. This paper presents simulation results of a H2O-LiBr absorption heat transformer (AHT) performance having a R123 vapor compression heat pump (VCHP) recovering heat at the AHT condenser which is transferred to the AHT evaporator. The heat capacity at the AHT absorber is 10 kW. The unit is used to upgrade heat from a solar water heating system by using a set of flat-plate solar collectors in parallel connection each having an area of 2 m2 with F (τα) R and R L F U of 0.802 and 10.37 W/m2 ⋅K , respectively. The weather data of Chiang Mai, Thailand are the input information for the calculation. For the AHT with VCHP assisted, the number of the solar collectors is around 18 units which is about 50% of that without the VCHP. The temperature at the AHT absorber could be booted up at a higher temperature level and the COP of the modified AHT is about 0.8 compared with 0.5 of the normal AHT when the AHT absorber temperature is in a range of 80-120 C o .