Abstract
We conducted energy and exergy analyses of an adsorption chiller to investigate the effect of recooling-water temperatures on the cooling capacity and Coefficient of Performance (COP) with variable cycle modes. We investigated both the effect of the recooling-water temperature and the dead state temperature on the exergy destruction in the chiller components. Our results show that there is an optimum reheat cycle mode for each recooling-water temperature range. For the basic single stage cycle, the exergy destruction is mainly accrued in the desorber (49%), followed by the adsorber (27%), evaporator (13%), condenser (9%), and expansion valve (2%). The exergy destruction for the preheating process is approximately 35% of the total exergy destruction in the desorber. By contrast, the precooling process is almost 58% of the total exergy destruction in the adsorber. The exergy destruction decreases when increasing the recooling-water and the dead state temperatures, while the exergy efficiency increases. Nonetheless, the exergy efficiency decreases with an increase in the recooling-water temperature at fixed dead state temperatures. The effect of the mass recovery time in the reheat cycle on exergy destruction was also investigated, and the results show that the exergy destruction increases when the mass recovery time increases. The exergy destruction in the adsorbent beds was the most sensitive to the increase in mass recovery time.
Highlights
Received: 18 March 2021Accepted: 9 April 2021Published: 13 April 2021Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland.The worldwide demand for cooling equipment is growing rapidly due to population growth, increased living standards, and rising temperatures due to climate change.Space cooling accounted for about 8.5% of world electricity consumption in 2019, and the electricity demand for space cooling is expected to increase by 50% by 2030 if there is no major efficiency improvement [1]
As the recooling temperature cannot be maintained at a low level, especially with a drycooled adsorption chiller, we aimed to investigate the energy and exergy of adsorption chillers at different recooling-water temperatures with different modes based on experimental results
The experimental temperature profile for the adsorption chiller components was exported to an excel sheet where the exergy was analyzed using Equations (4)–(13)
Summary
The worldwide demand for cooling equipment is growing rapidly due to population growth, increased living standards, and rising temperatures due to climate change. Space cooling accounted for about 8.5% of world electricity consumption in 2019, and the electricity demand for space cooling is expected to increase by 50% by 2030 if there is no major efficiency improvement [1]. The vapor–compression refrigeration cycles driven by electricity have the main global market share for air conditioning [2]. Driven cooling technologies, which can be driven by solar thermal energy and/or waste heat as absorption or adsorption cooling, are among the most common energy-saving solutions for cooling applications. The thermally driven cooling technology reduces greenhouse gas (GHG) emissions and ensures a higher indoor air quality [3]
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