Component Evaluation of a Separate Liquid Desiccant Air Conditioning System (SDCS)


This chapter aims to evaluate the performance of a separate liquid desiccant air conditioning system (SDCS) under a variety of environmental and operating conditions. SDCS component evaluation facilitates effective tri-generation system integration presented in Chap. 7.

Conclusions drawn from Chap. 5 demonstrate that the developed novel IDCS would not be suitable in a SOFC tri-generation system, particularly for building applications. This is due to a mass imbalance between the dehumidifier and regenerator, desiccant solution leakage and poor controllability of operating variables. Unlike the IDCS, the SDCS consists of three separate cores: a dehumidifier, regenerator and evaporative cooler. The SDCS has been developed in response to the IDCS shortcomings and with the intention that it will demonstrate greater potential for tri-generation system integration. The SDCS has been acquired from the company Intelligent Integration of Solar Air and Water (IISAW) in China, but has been tested at The University of Nottingham. The experimental work involves the testing of the heat powered SDCS under varying environmental and operating conditions in controlled laboratory conditions, using a potassium formate (CHKO2) liquid desiccant solution. As will be demonstrated in Chap. 7, there is limited control of the outputs for the SOFC CHP unit. As a result it is the operation of the SDCS that will need to be optimised to facilitate successful pairing of the two systems into an efficient and effective tri-generation system.

Detailed component testing of the SDCS under controlled laboratory conditions will facilitate the following:

  • (1) Highlight the impact changes in environmental and operational conditions have on the performance of the dehumidifier, regenerator and complete SDCS.
  • (2) Recording of the operational conditions in which the dehumidifier and regenerator are balanced i.e. the mass of water absorbed in the dehumidifier is equal to the mass removed in the regenerator. This will allow continuous operation of the SDCS across a range of working requirements.
  • (3) Selection of optimised operational conditions for the SDCS, with particular consideration to tri-generation system integration i.e. desiccant solution volumetric flow and hot water volumetric flow in the heating circuit (SOFC).

The chapter is split into three sections. Section 6.2 provides details of the SDCS experimental set-up, instrumentation and experimental method. Section 6.3 presents the SDCS experimental results and analysis. Section 6.4 concludes the chapter and discusses the implications for tri-generation system integration in an experimental setting. A published journal article, by the author, on the component evaluation of the separate liquid desiccant air conditioning system can be referred to here; Elmer et al. (2016b).

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