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Repeatability and reproducibility assessment of residential heat pump performance evaluation methodologies based on CSA EXP07 and AHRI 210/240.

Number: 2525

Author(s) : DHILLON P., WANG X., HORTON W. T., BRAUN J. E.

Summary

In the current testing and rating approach for performance evaluation of residential heat pumps (e.g., AHRI 210/240), seasonal energy efficiency (e.g., SEER) is estimated based on equipment performance measured in steady-state tests at different conditions and a degradation factor to account for the cycling losses during part-load conditions. In this current methodology, equipment controls are overridden with proprietary control settings from the manufacturer. Even though this current methodology provides a metric to compare the relative performance of equipment from different manufacturers, it does not capture the interaction of the integrated controls, equipment, and building dynamics. To address this aspect, a load-based testing methodology (CSA EXP07) has been developed with the motivation of capturing realistic equipment performance in a laboratory setting while operating similar to field application conditions by allowing the equipment to respond to a simulated virtual building load. To fully examine the applicability of the developed methodology as next-generation rating standards, it is crucial to assess the repeatability and reproducibility of the load-based testing approach. In this paper, repeatability and reproducibility assessments of both test methodologies, CSA EXP07 and AHRI 210/240, are presented based on round-robin test results of five different heat pumps of varied sizes and types from two different test facilities. Here, a summary of the overall seasonal performance repeatability and reproducibility is provided for both test methodologies along with a root cause analysis for the observed differences and recommendations for a next-generation rating approach. Reasonable to good repeatability was observed in EXP07 results in both labs when only comparing repeated tests that didn't involve test unit re-installation in between. However, poor reproducibility was observed when units were tested in different labs. On the other hand, AHRI 210/240 test results showed overall good repeatability as well as reproducibility. Some of the important factors that may have led to poor reproducibility of EXP07 results include issues related to the installation and setup of the unit for testing (e.g., instrumentation, refrigerant charge, duct static pressure, etc.), different interpretations, and implementations of the EXP07 draft standard, and different characteristics of the environmental chambers. Although these factors are also relevant for the current standard (AHRI 210/240), their impact on the results for load-based testing might be more significant because the draft standard is new and more complicated and the dynamic behavior of the unit with its integrated controls may be sensitive to some installation effects. Some of the differences in implementation will likely be resolved as the standard matures and personnel becomes more familiar with its application. Some of the issues with differences in facilities could be addressed by facility and test equipment improvements.

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  • Original title: Repeatability and reproducibility assessment of residential heat pump performance evaluation methodologies based on CSA EXP07 and AHRI 210/240.
  • Record ID : 30030766
  • Languages: English
  • Subject: Technology
  • Source: 2022 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2022

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