Heat Pump Water Heating System Using Variable Speed Compressor

a compressor and heat pump technology, applied in the direction of air heaters, indirect heat exchangers, lighting and heating apparatus, etc., can solve the problems affecting the performance of gas coolers and evaporators, and achieve the effect of improving the performance of heat exchangers, increasing energy exchangers per unit flow rate, and reducing mass flow ra

Inactive Publication Date: 2008-12-11
CARRIER CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]A variable speed drive controls the speed of the refrigerant flowing through the compressor. Varying the speed of the refrigerant flowing through the compressor changes the mass flow rate of the refrigerant in the system and affects the performance of the gas cooler and the evaporator. Decreasing the refrigerant mass flow rate causes the refrigerant to flow through the heat exchangers more slowly, increasing the energy exchanger per unit flow rate of the refrigerant and improving the performance of the heat exchangers. However, as the mass flow rate is reduced, the fan power per unit flow rate increases in the evaporator coil. As the power of the fan per unit flow rate increases, the coefficient of performance decreases. For any environmental condition, there is an optimal operating speed for the compressor that achieves the optimal coefficient of performance. In general, the higher the outdoor temperature, the lower the optimal speed of the compressor to obtain the optimal coefficient of performance.

Problems solved by technology

Varying the speed of the refrigerant flowing through the compressor changes the mass flow rate of the refrigerant in the system and affects the performance of the gas cooler and the evaporator.

Method used

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  • Heat Pump Water Heating System Using Variable Speed Compressor
  • Heat Pump Water Heating System Using Variable Speed Compressor

Examples

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Embodiment Construction

[0014]FIG. 1 illustrates a transcritical refrigeration system 20 including a compressor 22, a gas cooler 24, an expansion device 26, and an evaporator 28. Refrigerant circulates through the closed circuit system 20. Preferably, carbon dioxide is used as the refrigerant. Although carbon dioxide is described, other refrigerants may be used. Carbon dioxide has a low critical point, and systems utilizing carbon dioxide as the refrigerant usually run transcritically.

[0015]When operating in a water heating mode, the refrigerant exits the compressor 22 at a high pressure and a high enthalpy. The refrigerant flows through the gas cooler 24 and loses heat, exiting the gas cooler 24 at a low enthalpy and a high pressure. A fluid medium, such as water, flows through a heat sink 30 of the gas cooler 24 and exchanges heat with the refrigerant. A water pump 32 flows the fluid medium through the heat sink 30. The cold fluid 34 enters the heat sink 30 at the heat sink inlet or return 36 and flows i...

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PUM

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Abstract

A transcritical refrigeration system includes a compressor, a gas cooler, an expansion device, and an evaporator. Refrigerant is circulated though the closed circuit system. Preferably, carbon dioxide is used as the refrigerant. A variable speed drive controls the speed of the refrigerant flowing through the compressor. Varying the speed of the refrigerant flowing through the compressor changes the mass flow rate of the refrigerant in the system to optimize the coefficient of performance.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates generally to a heat pump or refrigeration system including a variable speed compressor that changes the speed of refrigerant flowing through the compressor to optimize the Coefficient of Performance (COP) of the system, which is usually defined as a ratio of the heating capacity to the electric power consumption of the compressor and the fan.[0002]Carbon dioxide is an environmentally friendly refrigerant that is commonly used in a refrigeration system. Carbon dioxide has a low critical point, and most refrigeration systems utilizing carbon dioxide as the refrigerant run transcritically or partially above the critical point. The pressure of a subcritical fluid is a function of temperature under saturated conditions (when both liquid and vapor are present). However, when the temperature of the fluid is higher than the critical temperature or supercritical, the pressure becomes a function of the density of the fluid.[0003]A...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F25B1/00F28D15/00F25B39/02
CPCF25B9/008F25B49/025F25B2309/061F25B2339/047F25B2500/19F25B2600/0253F25B2600/17Y02B30/741Y02B30/70
Inventor CHEN, YUZHANG, LILI
Owner CARRIER CORP
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