Experimental investigation on the performance of compact generator of R134a/DMF vapour absorption refrigeration system is presented. The system uses brazed plate heat exchangers as generator, condenser, absorber, evaporator and solution heat exchanger and has a rated cooling capacity of 1 kW. The influence of driving temperature ratio, driving pressure ratio, R134a mass fraction and solution two phase Reynolds number is studied. This kind of system can be operated with low grade thermal energy such as solar energy, waste heat, etc. The generator temperature is chosen accordingly between 353 K and 368 K. Desorption ratio and Sherwood number increase as the solution Reynolds number, solution initial mass fraction, and driving temperature ratio increase whereas they decrease as the driving pressure ratio increases. The performance of the compact generator at different operating conditions is presented. Based on the present data, empirical correlations for Nusselt number and Sherwood number are proposed. © 2012 Elsevier Ltd and IIR. All rights reserved.

A Mani

Department of Mechanical Engineering

ABSORPTION REFRIGERATION SYSTEM

ABSORPTION SYSTEM

BRAZED PLATE HEAT EXCHANGER

COMPACT GENERATORS

Cooling capacity

DESORPTION RATIO

Empirical correlations

Experimental investigations

GENERATOR

GENERATOR TEMPERATURE

Heat and mass transfer

INITIAL MASS

LOW GRADE

MASS FRACTION

Operating condition

PRESSURE RATIO

R134a

Sherwood numbers

SYSTEM USE

Temperature ratio

TWO PHASE

ABSORPTION REFRIGERATION

Desorption

Heat transfer

MASS TRANSFER

Nusselt number

Reynolds number

Vapors

Waste heat

Refrigerators

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

International Journal of Refrigeration

Heat and mass transfer during R134a desorption in compact generator and tubular generator have been compared experimentally. An R134a-DMF based vapour absorption refrigeration system is built with brazed plate heat exchangers as condenser, absorber, evaporator and solution heat exchanger with a rated cooling capacity of 1. kW. This kind of system can be operated with low grade thermal energy such as solar energy and waste heat. Generator temperature is chosen accordingly between 353. K and 368. K. Two types of generators in parallel, which are a brazed plate heat exchanger with chevron H-type plate channels and stainless steel concentric tubes, are investigated. Performances of the generators, at different operating conditions, have been compared, to explore the significance of compact generator for the improvement of absorption refrigeration technologies. Influence of solution flow rate, hot water inlet temperature, condensing temperature, evaporator temperature on generators is studied. Heat transfer rate, desorption rate, heat and mass transfer effectiveness increase with the hot water inlet temperature but decrease with increase in condensing temperature. Even though heat and mass transfer rates increase, heat transfer effectiveness and mass transfer effectiveness decrease with solution flow rate. © 2012 Elsevier Inc.

Experimental Thermal and Fluid Science

Comparison of compact and tubular generators performance for R134a-DMF

Fulltext

IOP Conference Series: Materials Science and Engineering

Review on Applications of NanoFluids used in Vapour Compression Refrigeration System for Cop Enhancement

A model of the absorption process in a vertical tubular bubble absorber working with R22-DMF, R22-DMA, R22-DMETEG, R22-DMEDEG and R22-NMP is developed using finite element method employing Galerkin's technique. The objective of this paper is to study the influence of the liquid and gas properties on the volumetric mass transfer coefficient. Analysis have also been done using ammonia-water as working fluid, the results obtained are compared with those in the literature and the agreement is found to be good. A correlation for mass transfer coefficient is proposed as a function of Reynolds number, Schmidt number and length to diameter ratio. The correlation can be used either in estimating the mass transfer rates or in fixing up any of the major design parameters namely length required for complete absorption and diameter.

Heat and Mass Transfer/Waerme- und Stoffuebertragung

Analysis of a bubble absorber working with R22 and five organic absorbents

A vapour absorption refrigeration system (VARS) in which a transfer tank replaces the conventional solution pump is analysed. Six fluid pairs with R22 as the refrigerant and different absorbents: DMA; DMF; DMETEG; DMETrEG; DMEDEG; and NMP are considered. Variations in COP, circulation ratio, percent mass of generated vapour utilised for transfer-tank operation, and minimum generator temperature are compared over a wide range of operating conditions. In general, R22-DMA, R22-DMF, and R22-DMETrEG are preferable for a transfer-tank operated VARS. At high generator temperatures or low condenser temperatures, R22-DMA gives the best overall performance. When the temperatures of the evaporator, absorber, and condenser are high, one may prefer R22-DMF as the working fluid. © 1995.

Renewable Energy

Performance of different working fluids in transfer-tank operated vapour absorption refrigeration systems

International Journal of Air-Conditioning and Refrigeration

NUMERICAL STUDIES ON VERTICAL TUBULAR GENERATOR IN VAPOR ABSORPTION REFRIGERATION SYSTEM

Flow boiling heat transfer of ammonia/water mixture in a plate heat exchanger

Applied Thermal Engineering

Experimental study of an ammonia–water bubble absorber using a plate heat exchanger for absorption refrigeration machines

Heat and mass transfer studies on compact generator of R134a/DMF vapour absorption refrigeration system

Journal	International Journal of Refrigeration
ISSN	01407007
Open Access	No