Development of working fluids used in absorption heat pump

Abstract

The first commercial absorption heat pump was designed by Ferdinand Carré in 1851 and a United States patent was issued in 1860. An absorption heat pump refers to a group of technologies that transfers heat from low temperature to high temperature while supplying heats as an energy source. The absorption heat pump has advantages from the viewpoints of energy saving and the protection of environment. It utilizes not electrical energy but heat energy source. And it does not use CFC refrigerants and is driven at low pressure. Because of these strong points, the absorption heat pump has received growing attention in recent years. Until now, $H_2O-LiBr$ has been the most widely used working pairs for absorption heat pump system. However, they still have disadvantages such as corrosion and solubility problems despite their high efficiency. In order to resolve the solubility problem, some additives such as lithium iodide and 1,3-propanediol were added into the lithium bromide solution. Also, The 2,2,2-trifluoroethanol(TFE) and quinoline system was chosen as a new organic working pair in order to overcome the known problems of $H_2O-LiBr$. TFE acts as a refrigerant and quinoline does as an absorbent. In order to optimally design an absorption heat pump and decide whether the modified lithium bromide-based absorbents and new organic working fluid, TFE-quinoline system, are suitable as the working pair for absorption heat pump or not, the density, viscosity and surface tension measurements together with the solubility, thermal conductivity, vapor pressure and VLE data must be required. These properties were closely related to the performance of an absorption heat pump. In this study, the various properties such as the density, viscosity, surface tension, differential heat of dilution and VLE data were measured to provide the basic information for the potential use.