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Heat and mass transfer studies on plate heat exchangers in R134a/DMF based vapour absorption refrigeration system.

Author(s) : MARIAPPAN S., ANNAMALAI M.

Summary

Renewed interest in vapour absorption refrigeration systems has increased due to their potential for utilization of waste heat, solar energy, etc. To improve the COP of these systems, it is necessary to study heat and mass transfer processes in absorption system components. This study describes the experiments carried out to analyse the heat exchangers performance of a vapour absorption refrigeration system of 1 TR capacity. A new combination of 1,1,1,2 tetrafluoroethane (R134a)-dimethyl formamide (DMF) is used as working fluid to overcome the limitations of well known working pairs, ammonia-water and lithium bromide-water. Plate heat exchangers are used as system components such as absorber, generator, evaporator, condenser and solution heat exchanger. Bubble absorption principle is employed in the absorber. Hot water is used as the heat source to supply heat to the generator. Experimentation has been conducted with a cooling capacity of 2 to 5 kW by varying the operating parameters viz., liquid refrigerant flow rate from 30 to 90 lph, solution flow rate from 160 to 1600 lph, hot water temperature from 67 to 95°C, cooling water temperature from 15 to 30°C. Water flow rates are maintained from 1250 to 2450 lph for hot water, from 1950 to 2050 lph for cooling water and 650 lph for chilled water. The following temperature range of operating parameters has been used, with generator temperature: 63-90°C, condenser temperature: 17-32°C, absorber temperature: 15-30°C and evaporator temperature: -2.5-10°C. Volumetric mass transfer coefficient and mass transfer effectiveness have been evaluated for the absorber. Heat transfer rate, heat transfer effectiveness and overall heat transfer coefficient have been evaluated for the absorber, generator and solution heat exchanger. Effect of circulation ratio on heat transfer rate, heat transfer effectiveness, mass transfer effectiveness, overall hear transfer coefficient and volumetric mass transfer coefficient are investigated.

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Details

  • Original title: Heat and mass transfer studies on plate heat exchangers in R134a/DMF based vapour absorption refrigeration system.
  • Record ID : 2011-0133
  • Languages: English
  • Publication date: 2010/07/12
  • Source: Source: Proc. 2010 int. Refrig. Air Cond. Conf., Purdue Univ.
    n. 2128; 8 p.; fig.; 13 ref.

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