The analysis of thermal and flow characteristics of the condensation of refrigerant zeotropic mixtures in minichannels

Abstract

The paper presents the results of experimental heat transfer and pressure drop during condensation of the single component refrigerant R134a and zeotropic mixtures R404A, R407C, and R410A in tube minichannels of internal diameter from the range 0.31-3.30 mm. The local values and the average of heat transfer coefficient and pressure drop in the whole range of the change in mass quality were measured. On the basis of the obtained test results there was illustrated the influence of the change of mass vapor quality, the mass flux density, and the inner diameter of channel on the studied parameters. These results were compared with the calculation results based on the relations postulated by other authors. The discrepancy range was ± 50%. On the basis of given test results own correlation was developed to calculate the heat transfer coefficient and pressure drop of tested refrigerants which presents the obtained results in a range of discrepancy of ±25%.

Safety aspects for the R290 (propane) as working medium in small air conditioning installations

“…In the coming years, only refrigerants such as: ammonia, carbon dioxide, propane, isobutane will be approved for use, from the group of hydrofluoroolefins there will be allowed only R1234ze, R1234yf [20]. All these natural refrigerants have been known in refrigeration for over 100 years, however, due to their flammability and explosiveness, they have lost the competition to synthetic agents such as R12 or R22, which are neither flammable nor toxic [3,4] and do not cause corrosion of the installation [25]. R32, R1234ze, R1234yf refrigerants are included in the newly created A2L group, non-toxic and moderately flammable substances [21,24,27].…”

Impact of selected thermal and flow parameters on flow boiling heat transfer in a minichannel

“…Bohdal et al [3] presented the results of experimental heat transfer during condensation of a single component refrigerant R134a and zeotropic mixtures R404A, R407C and R410A in tube minichannels. The heat transfer coefficient was dependent on thermal parameters of the condensation process (including saturation temperature), inner diameter of the tubular minichannel, mass flux and vapor quality.…”

Modeling of Pressure Drop During Refrigerant Condensation in Pipe Minichannels

“…However, this is associated by an increase of flow resistance. In the case of minichannels, this raises a certain calculation problem in the design of mini heat exchangers [5,6]. It should be noted that, in the market, there are new types of refrigerants that have different physical and chemical properties, which complicate the calculation procedures.…”