Solar absorption cooling feasibility

This paper presents an investigation of an ammonia‐water absorption cycle for solar refrigeration, airconditioning and heat pump operations at higher heat supply temperatures. The system consists of a solar driven generator, rectifier, condenser, evaporator, absorber and heat exchangers for preheating and subcooling within the system. A steady state thermodynamic cycle analysis based on mass and heat balances along with the state equations for the thermodynamic properties of the ammonia‐water mixture has been carried out. A numerical computer simulation of the system with input component temperatures, refrigerant concentration/mass flow rate and effectiveness of the heat exchangers has been made to evaluate the relative heat transfer rates (i.e. coefficients of performance) and the mass flow rates for the cooling/heating modes. It is found that unlike the low generator temperature behaviour the coefficients of performance for both cooling and heating modes are reduced at higher generator temperatures. However, an increase of condenser temperature for each mode of operation improves the performance of the systems at higher generator temperatures. A choice for keeping the absorber temperature equal to/lower than that of the condenser is also predicted at lower/higher generator temperatures, respectively. In general the results are more pronounced for the refrigeration mode than for the heat pump mode and are least effective for the airconditioning mode.

Theoretical analysis of ammonia-water absorption cycles for refrigeration and space conditioning systems

Kaushik

Bhardwaj

1982

Energy balance of solar absorption and vapour compression cooling systems

Ayyash

Suri

1983

Solar absorption cooling systems are viewed as potential alternatives to fossil‐fuel‐based conventional cooling systems. This view is investigated in this paper from the point of view of the energy balance of solar absorption and conventional systems. The paper investigates the primary energy needs of three cooling systems; dry and wet cooled vapour compression systems and wet cooled solar absorption. The sources of energy demand in the three systems are identified and their primary energy needs determined. The paper, then, investigates the conditions under which the energy inputs to the solar system breaks even with the other two systems. The investigation is conducted with particular reference to the operational and environmental conditions in Kuwait.

Thermal modelling and parametric study of two stage absorption refrigeration and air-conditioning systems

Kaushik¹,

Kumar²,

Chandra³

1985

This paper presents a thoermodynamic assessment of two stage absorption refrigeration and air‐conditioning systems. Two working fluids, namely water‐LiBr and NH3‐H2O as refrigerant‐absorbent combinations have been considered for the production of different cooling temperatures. Both the systems are assumed to be operated with hot water available from solar collectors. Thermal modelling and a parametric study of a two stage absorption system, based on thermodynamic analysis aided by computer, have been carried out in detail. It is found that the cascading of two stage absorption systems (in which the first stage evaporator produces cooling water to be circulated in the absorber of the second stage) can be easily operated to produce much lower temperatures suitable for refrigeration and air‐conditioning applications. The COP of a two stage absorption system is lower than that of a single stage; however, the second stage can be operated with lower generator temperatures than the first stage. However, there is an advantage for a two stage system because of the slow fall‐off in COP at higher generator temperatures.