Measurement of thermodynamic properties and cycle analysis of new working fluids used in air-cooled absorption heat pump

Abstract

The absorption heat pump has received growing attention in the past years from the areas of refrigeration and air-conditioning, especially in the aspect of energy saving and the protection of environment. At the present time, ozone depletion and the concomitant regulation of CFC refrigerants has created an interest in non-ozone-depleting refrigerants for use in commercial sized chillers. Also, the emphasis on electrical demand especially in the summer, has created an interest in cooling technologies which are driven by other than electrical means. One older technology which has found resurgence in this new climate is absorption cooling. The performance and efficiency of an absorption chiller are determined to a large degree by the properties of the working fluids. In order to operate the air-cooled absorption chiller, the lithium bromide+1,3-propanediol+water ($LiBr/HO(CH_2)_3OH$ mass ratio=3.5), the lithium bromide+diethanolamine+water ($LiBr/(HOCH_2CH_2)_2NH$ mass ratio=3.5), the lithium bromide+lithium nitrate+1,3-propanediol+water ($LiBr/LiNO_3$ mole ratio=4.0 and $LiBr/HO(CH_2)_3OH$ mass ratio=3.5), and the lithium bromide+calcium nitrate+water ($LiBr/Ca(NO_3)_2$ mass ratio=1.0) systems were selected as new working fluids. For these selected systems, solubilities and vapor pressures were measured and D\"{u}hring charts were constructed. From the Duhring charts for the selected systems, it was known that the lithium bromide+1,3-propanediol+water system and the lithium bromide+diethanolamine+water system can be operated with appropriate operation range. For more detailed cycle analysis, heat capacities of the lithium bromide+1,3-propanediol+water system and the lithium bromide+diethanolamine+water system were measured, then the enthalpy - concentration charts were constituted with the results of D\"{u}hring charts. Through the cycle analysis, the absorption cycle using the lithium bromide+1,3-propanediol+water system and the lithium bromide+diethanolamine+w...