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Model of heat pump water heater operating on a new storage heat pump cycle to achieve higher operating range.

Number: 2256

Author(s) : PATEL P., ELBEL S.

Summary

Heat pumps for water and space heating applications have become more attractive as they support the decarbonization goals due to their higher efficiency as compared to electric resistance heating. However, heat pump systems are often restricted to operate within a certain temperature range due to the limits on compression ratio and discharge temperature. With the aim of improving the operating temperature range of a heat pump system, a new storage heat pump concept is proposed.
Model of a conventional R134a heat pump water heater (HPWH) system with wrap-around condenser coil is developed and this conventional system model is then extended to develop the model for a HPWH system operating on the new storage heat pump cycle. The system model consists of a quasi-steady vapor compression cycle model linked with a transient water tank CFD model to obtain system performance at various time intervals.
Implementation of the new concept requires a split-condenser design, an energy storage element and the system operation in two different modes. In Mode I, the ambient air acts as the heat source for the evaporator and the water inside the tank is heated from a low to intermediate temperature. Then the system operation shifts to Mode II, where a throttling valve splits the wrap-around coil into condenser and evaporator. Here, the intermediate temperature water in the lower tank region acts as the heat source and this allows the water in the upper region to reach the required high temperature. System performance in Mode II will depend on parameters such as split-ratio for wrap-around coil, compressor speed and the time at which operation is switched between two modes. Modeling results for the system operating on storage heat pump cycle are presented for a particular combination of these parameters, and compared with performance of conventional system.

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  • Original title: Model of heat pump water heater operating on a new storage heat pump cycle to achieve higher operating range.
  • Record ID : 30030630
  • Languages: English
  • Subject: Technology
  • Source: 2022 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2022

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