Thermodynamic analysis of lithium bromide absorption chiller driven by geothermal energy
The use of geothermal energy as a heat source to drive vapor absorption chillers has been receiving more interest. Geothermal energy is sustainable, economically viable and environmentally friendly. Absorption chillers powered by geothermal energy are still in their development phase. In this work, a lithium bromide absorption chiller operated with a geothermal heat source will be thermodynamically analyzed. The focus will be on the solution heat exchanger performance, in particular, the effect of geothermal heat source fluid temperature as well as mass flow rate on the absorption chiller coefficient of performance (COP). The effectiveness of the solution heat exchanger will be also studied and evaluated. Preliminary results showed that as the pressure in geothermal water vapor separator increased from 0.23 to 0.45 MPa, the absorption chiller cooling load increased by 28% while the COP decreased by only less than 1.4% at the same condenser pressure.
Energetic Analysis of Single Stage Lithium Bromide Water Absorption Refrigeration System
A detail energetic analysis of LiBr-H20 absorption refrigeration system of 140 kW cooling capacity is investigated in the present study. The effect of exit temperatures of main components on heat load, circulation ratio, pump work, COP, COP rev and ηex are analyzed at different operating conditions. The result shows the heat load on generator and absorber increases with rise of generator and condenser exit temperature and it reduces when both evaporator and generator exit temperature are simultaneously increased. COP value is found high at lower condenser exit temperature and the average value of COP reduces by 8.1% when condenser temperature is increased along with generator exit temperature. As condenser exit temperature increases, the COPrev linearly decreases with it which results in hike of ηex by 38%. COP increases linearly with rise of evaporator and generator exit temperature but ηex keeps on decreasing with it. It was also found in the study that as the condenser and generator exit temperature increases, COP starts decreasing gradually but ηex first increases linearly with increase in the condenser exit temperature and then it starts to fall at the higher condenser exit temperature
Solar refrigeration options – a state-of-the-art review
Abstract A state-of-the-art review is presented of the different technologies that are available to deliver refrigeration from solar energy. The review covers solar electric, solar thermal and some new emerging technologies. The solar thermal systems include thermo-mechanical, absorption, adsorption and desiccant solutions. A comparison is made between the different solutions both from the point of view of energy efficiency and economic feasibility. Solar electric and thermo-mechanical systems appear to be more expensive than thermal sorption systems. Absorption and adsorption are comparable in terms of performance but adsorption chillers are more expensive and bulkier than absorption chillers. The total cost of a single-effect LiBr–water absorption system is estimated to be the lowest.