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Experimental analysis of R134a and R1234ze(E) flow boiling inside a roll bond evaporator.

Number: pap. 2220

Author(s) : RIGHETTI G., ZILIO C., LONGO G. A.

Summary

This paper presents an experimental study of R134a and R1234ze(E) inside an off the shelf roll bond evaporator, commonly used for small size domestic refrigerators. The evaporator was mounted inside a climate dark chamber where ambient temperature and humidity were maintained stable during the tests. To control the inlet conditions (evaporation temperature, inlet quality, refrigerant mass flow rate) it was used a water cooled miniature scale vapor cycle system with R134a and R1234ze(E) as working fluids. By means of an IR-thermo-camera and thanks to 16 thermocouples collocated on the back of the evaporator, the whole roll bond temperature field was investigated under different working conditions. During the experimental tests the refrigerant mass flow rate was varied by regulating the compressor speed, while ambient temperature and evaporation temperature were kept as constant. From the IR pictures it was possible to delineate the super heating region and to point out the areas of the evaporator in which heat transfer is less efficient depending on the fluid and on the working conditions. The data acquired from the vapor cycle system (i.e. condensation and evaporation pressure, evaporator inlet quality, vapour superheating, refrigerant mass flow rate) coupled with the IR thermo-camera images allowed to evaluate the behavior and the efficiency of the roll bond. Since the data were collected maintaining the same operating conditions in term of ambient temperature and humidity, heat flow rate and evaporation temperature, it was possible to highlight differences among the two refrigerants in terms of mass flux. Furthermore, on the basis of the IR images and of the thermocouples measurements, an average heat transfer coefficient was defined and determined both on the air and the refrigerant side. The average heat transfer coefficients of the two refrigerants are compared and outlined in the paper.

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Pages: 10 p.

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Details

  • Original title: Experimental analysis of R134a and R1234ze(E) flow boiling inside a roll bond evaporator.
  • Record ID : 30013352
  • Languages: English
  • Source: 2014 Purdue Conferences. 15th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2014/07/14

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