24-11-2012, 04:04 PM
Mathematical Modelling of aqua-ammonia vapour absorption system
Mathematical Modelling.ppt (Size: 349 KB / Downloads: 46)
Objective
To study the nature of variation of Coefficient of Performance, heat added to generator and heat extracted from absorber with different operating temperature.
Comparison of Coefficient of Performances of a vapour absorption refrigeration system with the Coefficient of performance of vapour compression refrigeration system for fixed condenser and evaporator temperature
Literature Survey
VARS is a system of refrigeration that uses a heat source (mainly waste heat source) to provide the energy needed to drive the cooling system.
Properties of working fluid required
The difference in boiling point between the pure refrigerant and the mixture at the same pressure should be as large as possible.
Refrigerant should have high heat of vaporization and high concentration within the absorbent.
Transport properties that influence heat and mass transfer, e.g., viscosity, thermal conductivity, and diffusion coefficient should be favorable.
The mixture should be chemically stable, non-toxic, non-corrosive environment friendly and non-explosive.
Key Characteristics of Ammonia- Water Absorption System
Generally used for applications requiring temperatures in the range of -40ºC to +5ºC. The preferred heat source temperature is 95ºC to 180ºC.
Available as very small pump-less systems to large refrigeration capacities.
These chillers do not suffer from the problem of crystallization and operate at moderate pressures.