System options for cooling of buildings making use of district heating heat

Abstract

Issues stemming from district heating utilization during summer periods and the conversion of low-temperature heat into cold in adsorption chillers have been investigated in this paper. Due to the high vulnerability of adsorption chillers to ambient conditions, in the case of relatively low ambient temperatures, adsorption-based air-conditioning systems would be characterized by excessive cooling power. Moreover, adsorption chillers are also characterized by high investment costs and big time constants, and the vulnerabilities found in their regulatory processes have yet to be sufficiently investigated. The authors recommend the application of hybrid air-conditioning systems, consisting of adsorption and compressor chillers. The adsorption chiller works as a base while the compressor chiller contributes missing cooling power, working as a regulation unit. Sixteen configurations of the hybrid air-conditioning system have been analysed. It has been shown that 100 kW cooling power hybrid air-conditioning system, with respect to its configuration, enables the utilization of 0.5 to 0.9 TJ of low-temperature heat per year, while simultaneously providing comfortable air-conditioning. The authors have concluded that the adsorption share in the analysed hybrid system should not exceed 50%.