The schematic of the integrated system is shown in Fig. 1. The main components of the system are: (1) solar collector and hot water tank, (2) absorber or dehumidifier, (3) desorber or regenerator, and (4) indirect evaporative cooler.

HWT — hot water storage tank, R — regenerator, A — absorber,
DHW — domestic hot water, CSS — concentrated solution storage,
DSS — diluted solution storage
Fig. 1. Schematic of the Integrated Thermal System

The system will provide hot water all year round, space heating during the heating season and cooling / dehumidification during the cooling season. The hot water service should be available all year round and the system operation can be divided into two different modes, Fig. 1: (a) cooling / dehumidification and water heating and (b) space and domestic hot water heating.

Mode 1: Space cooling / dehumidification and Water Heating

In this mode, the air is dehumidified by contacting it with the concentrated desiccant solution in the absorber before being cooled by an indirect evaporative cooler. The regenerator is used to reconcentrate the liquid desiccant solution using the hot water from the tank. The dehumidification system is assumed to operate when the air outlet temperature from the indirect evaporative cooler alone exceeds 27°C.

Mode 2: Space Heating and Hot Water Heating

For domestic water heating, the hot water stored in the tank is used to indirectly heat the mains water on demand. Space heating is provided by circulating water from the storage tank into the regenerator (used as a heat exchanger) in order to indirectly heat the air entering the building. Heat in the exhaust air from the building can be recovered by the absorber to preheat the outside air to be used for heating. In this mode, the absorber is inactive.

TNRSYS [7] was used as a simulation tool. For the purpose of analysis, an array of evacuated tube collectors were assumed to provide the heating required to satisfy the cooling (CL), space heating (HL) and domestic hot water loads (DHW). The system has the following instantaneous efficiency curve coefficients: a0 = 0.717, a1 = 5.472 kJ/hr. m2K, and a2 = 0.0306 kJ/hr. m2K2 [8]. The system has the following values of incident angle modifier (IAM):