SPECIFIC HEAT CAPACITY OF LIBR+H_2O AND LIBR+H_2O+TEG SOLUTIONS AT TEMPERATURES FROM 308K TO 343K AND ATMOSPHERIC PRESSURE

摘要

Water is regarded as an important natural refrigerant, and LiBr+H_2O or LiBr+H_2O+glycols solution plays anrnimportant role in the absorption refrigeration systems and dehumidification cooling. Isobaric specific heatrncapacity (Cp) of LiBr+H_2O and LiBr+H_2O+triethylene glycol (TEG) solutions are presented in this context. Thernmeasurement is run on a Calvet calorimeter in this work. The calorimeter consists of two vessels of the same sizernin an isolating chamber surrounded by heating elements, and operates with temperature precision of ±0.05 K andrncalorimetric precision of ±0.1 %. Firstly, Cp of LiBr+H_2O solution is measured at temperatures from 308 K torn343 K, and P=0.1 Mpa, and the mass fraction of LiBr+H_2O solution ranges from 20% to 60 %. The results arernanalyzed and compared with the values of previous articles by other authors, and permit to conclude that thernCalvet calorimeter we used is capable of accurate measurements of Cp of liquids. In addition, Cp ofrnLiBr+H_2O+TEG (LiBr/TEG mass ratio = 0.5) solution is measured at temperatures from 308 K to 343 K andrnatmospheric pressure, and the absorbent concentration ranges from 30 % to 70 %. Finally, the measuring data isrncorrelated and a universal Cp formula is obtained as a function of temperature and composition of LiBr+H_2O orrnLiBr+H_2O+TEG solution by a least-squares method. The correlation formulas give satisfactory accuracy forrnmost engineering-design calculations.