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LOST WORK AND ITS REDUCTION IN REFRIGERATION PROCESSES.

Author(s) : BREDA-SMITH M. van

Summary

LOST WORK IS DEFINED AS THE DIFFERENCE IN ENERGY BETWEEN THE REVERSIBLE IDEAL AND THE ACTUAL PROCESS CONSIDERED INDEPENDENTLY FOR EACH PROCESS IN A VAPOUR COMPRESSION REFRIGERATION CYCLE. THIS IS ILLUSTRATED BY COMPARING AN EXPANSION VALVE WITH AN ISENTROPIC EXPANSION. TWO SYSTEMS ARE ANALYSED IN FULL, A SINGLE STAGE COMPRESSION SYSTEM AND ONE HAVING TWO STAGES ANDAN ECONOMISER (FLASH PRECOOLER). BOTH HAVE EFFICIENCIES OF APPROXIMATELY 30% COMPARED TO A REVERSIBLE IDEAL. EACH PART OF A SYSTEM IS THEN EXAMINED FOR PERFECTIBILITY. AN EXPANSION VALVE MAY POSSIBLY BE REPLACED BY AN EXPANSION ENGINE OR, MORE PRACTICALLY IN LARGE SYSTEMS BY DIFFERENTIAL BATCH EXPANSION WITH SEPARATE COMPRESSION OF THE FLASH VAPOUR. LOST WORK IN THE CONDENSER IS MAINLY A FUNCTION OF VAPOUR DESUPERHEATING WHICH MIGHT BE MORE ECONOMICALLY OVERCOME BY WET COMPRESSION OR OIL / REFRIGERANT COOLING IN A SCREW COMPRESSOR. EVAPORATOR PERFORMANCE MAY BE IMPROVED WHEN THE COOLING RAL STEPS, I.E. EVAPORATORS IN SERIES. AN ALTERNATIVE IS TO USE A CONTINUOUSLY RUNNING SYSTEM ON BATCH PROGRESSIVE COOLING. COMPRESSORS MAY BE IMPROVED BY ELIMINATING CAPACITY CONTROL DEVICES WHICH ARE ALWAYS INEFFICIENT AND BY THE POSSIBILITY OF LIQUID INJECTION TO REDUCE DISCHARGE ENTHALPY. D.W.H.

Details

  • Original title: LOST WORK AND ITS REDUCTION IN REFRIGERATION PROCESSES.
  • Record ID : 1981-1160
  • Languages: English
  • Publication date: 1980/06/17
  • Source: Source: Frigair '80, Pretoria
    pap. 16; 18 p.; 16 fig.; 2 tabl.; 5 ref.

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