Feasibility analysis of a hot water solar system coupled to an absorption heat transformer

Parabolic Trough Collectors (PTC) provides thermal solar energy at medium temperature, and in order to increase the thermal level, the solar system can be coupled to upgrading devices, such as Absorption Heat Transformers (AHT). In this paper, a feasibility analysis of the PTC system operating as thermal source of an AHT is described. The PTC and AHT units were tested and, based on the experimental data of each system, a heat transfer analysis was carried out in order to propose a single system. Two case studies were analysed: In the first, the evaporator temperature was close to the generator temperature (84.6 and 85.2 °C respectively) and a simultaneous flow from the heat source was used; in the second case, the evaporator temperature was lower than the generator temperature (79.6 and 86.7 °C respectively) and a serial flow from the heat source was proposed. Results show that, for the absorber temperature of 101 °C, the calculated generator and evaporator heat loads were 1.50 and 1.34 kW respectively in Case 1, and 0.86 kW for both components in Case 2. For Case 1, the PTC system required 6.0 m2 in order to provide two mass flows of 6.00 × 10−02 and 5.35 × 10−02 kg/s for generator and evaporator at 89 °C. For Case 2, one mass flow of 6.60 × 10−02 kg/s at 89 °C for generator and evaporator must be satisfied by a 3.7 m2 PTC system.