Experimental evaluation of a liquid desiccant air conditioning system for tri-generation/ waste-heat-driven applications

Abstract

This paper aims to evaluate the application of liquid desiccant air conditioning technology in the development of efficient and effective tri-generation/waste-heat-driven system applications, in particular with regard to solid oxide fuel cell (SOFC) technology. Using operational thermal input values typical of an SOFC combined heat and power (CHP) system, the paper's evaluation validates the concept of integrating SOFC and liquid desiccant air conditioning technology into an efficient and effective first-of-its-kind tri-generation system. This is due to good dehumidification capacity and effective regeneration of a potassium formate solution at a 0.65-0.7 solution mass concentration. Conclusions of the paper's evaluation include: (1) effective instantaneous balancing of the dehumidifier and regenerator across a range of environmental and operational values, (2) operation of the dehumidifier is dictated, to some degree by the available thermal energy (CHP prime mover, process heat), (3) encouraging thermal COP values, for a system of this scale, in the range of 0.4-0.66 are achievable with a low-grade thermal input (45-60°C) typical of an SOFC CHP system and (4) potential for non-synchronous operation in a tri-generation system context, bringing about improvements to peak cooling output and total system efficiency. The compact nature and effective use of low-grade thermal energy means the liquid desiccant air conditioning system demonstrates significant potential for integration with other CHP prime mover technologies such as internal combustion engine or any (waste) heat source with a similar thermal quality/quantity. A future paper by the authors will present a novel SOFC liquid desiccant tri-generation system.