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Performance investigation of a residential air source heat pump with partial variable speed electronics driving a PSC rotary compressor as single stage, two stage and variable speed compressor.

Number: 2342

Author(s) : YANG B., CHRETIEN L.

Summary

A variable speed residential air source heat pump system generally operates with a variable speed compressor controlled by a fully variable speed drive. This type of system has the capability to operate the compressor over a wide speed range (from very low speed to over-speed) commanded by the algorithm from a system controller. To achieve this wide range of operation, the electronics components must be rated to reach the maximum output power (over 7kW for a 5 ton system). Additionally, the drive is permanently conditioning line power to energize the compressor, constantly incurring losses in the power electronics.
A novel partial variable speed compressor drive is presented that overcomes the above mentioned challenges (high power rating, electronics losses) of existing fully variable speed solutions, taking into account that typical HVAC systems would operate above 90˚F ambient for approximately only 7% of the time. With the proposed solution, the system would operate with line power at ambient temperatures higher than 90˚F (AHRI 210/240-2023, Table 13). Unlike fully variable speed compressors driven with brushless DC (BLDC) motors, the solution uses a regular single speed rotary type compressor driven by an induction (Permanent Split Capacitor, PSC) motor. A lower power rated (2.5kW for a 5T system), output optimized, variable speed compressor drive is used to control the compressor.
The performance of this new solution is validated via psychrometric room testing following the AHRI 210/240-2023 standard. A single speed two-stage PSC rotary compressor is selected to operate with the partial variable speed drive in this system. Two scenarios are tested including variable speed modulation of the compressor speed as a single stage (high displacement) and as a two-stage (high and low displacements). The results show that the air source heat pump system can achieve close to 5 points of SEER2 rating improvement with the addition of this low power drive to the standard single stage rotary compressor, without redesigning the heat exchangers or outdoor cabinet. Finally, potential benefits of operating the compressor at low displacement stage with the proposed drive are discussed.

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Details

  • Original title: Performance investigation of a residential air source heat pump with partial variable speed electronics driving a PSC rotary compressor as single stage, two stage and variable speed compressor.
  • Record ID : 30033171
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 20th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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