Dynamic Simulation of an Absorption Cooling System with Different Working Mixtures

Abstract

High consumption of electricity represents an economic and social problem in warm places, caused by the massive use of cooling machines. Absorption systems are a sustainable method for air conditioning applications. However, environmental conditions should be analyzed to avoid crystallization problems of the working mixture. This article presents a thermal analysis of a solar absorption cooling system in dynamic conditions using NH 3 -H 2 O, H 2 O-LiBr, NH 3 -NaSCN, NH 3 -LiNO 3 , and H 2 O-LiCl working mixtures using Equation Engineering Solver (EES) and TRaNsient SYstem Simulation (TRNSYS) software. A solar collector area of 42.5 m 2 was selected to carry out the thermal analysis. The results showed that H 2 O-LiCl obtained the maximum solar (0.67) and minimum heating (0.33) fraction. However, it obtained the maximum lost heat fraction (0.12), in spite of obtaining the best coefficient of performance (COP) among the other working mixtures, due mainly to a crystallization problem. The gain fraction (GF) parameter was used to select the adequate solar collector number for each working mixture. NH 3 -LiNO 3 and NH 3 -H 2 O obtained the highest GF (up 6), and both obtained the maximum solar (0.91) and minimum heating (0.09) fraction, respectively, using 88.8 and 100.4 m 2 of solar collector area, respectively.

New Perspective on Performances and Limits of Solar Fresh Air Cooling in Different Climatic Conditions

“…Similar values are reported in the literature for the solar hot water temperature: 80-90 °C [28], 55-135 °C [8], 90-100 °C [15], 85-90 °C [31], 84-120 °C [14].…”

“…Between several other solar cooling technologies, the solar absorption cooling systems (SACS) were found to be the most energy efficient for 6 major cities in Australia [6]. SACS are considered a sustainable solution as solar driven air conditioning equipment particularly in warm climates, even if problems related to these systems still exist [7,8]. Based on the coefficient of performance (COP) SACS are more efficient than other systems, such as the adsorption ones [9].…”

“…This concern is a major operating issue of these systems. The possibility of avoiding the crystallization problem was investigated in some studies including [8,17]. Despite these concerns, recommendations related to the accepted operating conditions capable to avoid crystallization in solar LiBr-H2O SACS are not easily available in literature.…”

New Perspective on Performances and Limits of Solar Fresh Air Cooling in Different Climatic Conditions

“…This concern is a major operating issue of these systems. The possibility of avoiding the crystallization problem was investigated in some studies including [8,17]. Despite these concerns, recommendations related to the accepted operating conditions capable of avoiding crystallization in solar LiBr-H 2 O SACS are not easily available in literature.…”

“…Between several other solar cooling technologies, the solar absorption cooling systems (SACS) were found to be the most energy efficient for six major cities in Australia [6]. SACS are considered a sustainable solution for solar driven air conditioning equipment, particularly in warmer climates, even though some problems related to these systems still exist [7,8]. Based on the coefficient of performance (COP), SACS are more efficient than other systems, such as the adsorption ones [9].…”