Application Analysis of Medium Temperature Solar Refrigeration System in Civil Buildings

The lithium bromide absorption refrigeration system with medium temperature solar collector as driving heat source was built, and the refrigeration performance of the system was tested and analyzed. The medium-temperature solar collector adopts all-glass vacuum solar collector tube with heat-conducting oil as medium, and the inside of the vacuum tube is composed of heat-conducting medium flow channel on the sunny side and aluminum silicate insulation cotton on the backlight side. Through test and analysis, the medium temperature solar collector of the system can provide stable heat source, and the maximum temperature of solar heating can reach above 150°C in sunny weather and about 80°C in cloudy days. The generator driving heat of the system is stable and efficient. The driving heat of lithium bromide absorption refrigerator is higher than 200 MJ/h, and can reach 300 MJ/h in some periods. The COP of the system can be kept above 0.6 during stable operation, but when the driving temperature of the generator is higher than 80°C, the COP of the system basically does not increase with the increase of the driving temperature.

A Thermodynamic Performance Analysis of Triple Effect Vapour Absorption Refrigeration System Using LiBr-H2O

Being an eco-friendly system and a cheaper way to produce cooling effect absorption refrigeration system (ARS) is becoming more popular as it can produce higher cooling capacity than vapor compression refrigeration systems, and it can be powered by other sources of energy (like waste heat from gas and steam turbines, or can utilizes renewable source of heat by sun, geothermal, biomass) other than electricity. In the recent years, the interest in absorption refrigeration system is growing because these systems have environmentally friendly refrigerant and absorbent pairs. In this study, a detail energetic analysis of triple stage LiBr-H20 absorption system using First law of thermodynamics is done. An Energy Equation Solver code are used to simulate the computer program is developed for the cycle and results are validated with past studies available is also done. Mass, energy and exergy balance equations and the various complementary relations constitute the simulation model of the triple effect refrigeration system. Further, the effect of exit temperature of generator, absorber, condenser and evaporator on COP, solution concentration and other parameters are studied. It was found in the study that COP increases with increasing the generator exit temperature keeping the absorber exit temperature constant but when the absorber exit temperature is increased COP tends to decrease and the concentration of weak solution leaving HP generator (Xw3), MP generator (Xw2) and LP generator (Xw1) also increases with increase in generator exit temperature, while it decreases with increase in condenser exit temperature. Keywords: Absorption Refrigeration System (ARS), LiBr + H2O, COP, solution concentration, Energy Equation Solver code, energetic analysis, triple effect refrigeration system.

Electrical conductivity of concentrated LiBr Ethylene-Glycol and water ternary system

LiBr/H2O as working pair in absorption chiller is widely used in the absorption refrigeration system, and the electrical conductivity is used as secondary properties as an empirical relation with temperature and concentration as a simple method to measure the concentration. In this paper, another working pair Carrol/H2O is chosen, more suitable for air-cooled cycles. Carrol contains ethylene glycol and LiBr with a mass ratio at 4.5:1 and has advantages of low risk of crystallization and reduce the LiBr charge. The working range for the LiBr/H2O solution is temperature 25-80°C, at concentration 50–64%, in term of Carrol/H2O system, the temperature range is 25-80°C, concentration range is 50%-75%. The electrical conductivity will be measured according to the working range and a typical used solution extracted from an absorption chiller prototype will also be measured to compare with the experimental result.