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Experimental characterization of a condensing units’ performance under a controlled refrigerant leakage.

Number: 2443

Author(s) : HADDAD E., ZOUGHAIB A.

Summary

The European regulation has set a series of limitation to reach the objective of reducing the Global Warming Potential (GWP) emissions. Among these limits, the ban of Hydrofluorocarbons (HFC) refrigerants having a GWP higher than 2500 starting 2020. To replace these refrigerants, a new family of refrigerants was invented: hydro-fluoro-olefins (HFOs), also new systems were developed using CO2. In this paper, we present the outcome of a testing campaign aiming to compare the performance, operating range and cost of two condensing units of a rated capacity of 8kW cooling a secondary glycol loop. One of these machines, initially operated with R-404A, is operated with low GWP blends containing HFO while the other is using CO2. The comparison includes traditional HFC refrigerant (R-404A), 3 different commercial HFOs containing blends and transcritical CO2. The comparison is made using different ambient temperatures to have a fair comparison. A special focus is done analysing the glide impact on the condensing unit behaviour and performance. The glide matching blend (R-454C) shows an increased performance while the other refrigerants are penalized. Finally, HFOs containing blends were found more efficient and capable of operating at a wider temperature range co The European regulation has set a series of limitation to reach the objective of reducing the high Global Warming Potential (GWP) gases emissions. Among these limits, the ban of Hydrofluorocarbons (HFC) refrigerants having a GWP higher than 2500 starting 2020 and a stringent leakage control on refrigeration equipments. Many continuous leakage detection technologies exist but they are not applicable in many cases such as open space or outside equipments. A software based leak detection technique may be interesting in these cases. This technique is based on machine data monitoring and data derived models. In order to be more precise and avoid outlier alarms, the sensitivity of usually measured variables such as temperatures and pressures should be correlated to refrigerant charge level. In this paper, an experimental campaign is performed on a condensing unit under a controlled leakage. The tested condensing unit having a piston compressor of 16 m3/h is cooling a secondary glycol loop. It has a thermostatic expansion device and a liquid receiver. The condensing unit is first charged in a way to overfill the liquid receiver. A leakage is simulated by connecting the receiver’s outlet to a micro valve that delivers the refrigerant to an external empty cylinder continuously weighted. Different usually measured variables are recorded. These are pressures and inlet and outlet temperatures of condenser and suction temperature. Compressor electricity consumption and the produced cooling capacity are also monitored. Results show the sensitivity of the high pressure and the subcooling to the charge level until the liquid receiver starts to be partially filled. The cooling capacity is also impacted.mpared to CO2.

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Pages: 8

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Details

  • Original title: Experimental characterization of a condensing units’ performance under a controlled refrigerant leakage.
  • Record ID : 30028481
  • Languages: English
  • Subject: Technology
  • Source: 2021 Purdue Conferences. 18th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2021/05
  • Document available for consultation in the library of the IIR headquarters only.

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