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Oil return control method of direct expansion type earth source heat pump

A ground source heat pump and oil return control technology, applied in heat pumps, refrigerators, refrigeration components, etc., can solve problems affecting system operation, accumulation of lubricating oil in underground heat exchanger pipelines, and inability to ensure complete oil return, etc., to achieve guaranteed Good oil return efficiency and effect, ensuring stable and efficient operation

Inactive Publication Date: 2009-02-11
HUNAN UNIV
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Problems solved by technology

However, the usual oil return measures cannot guarantee complete oil return, and lubricating oil may still accumulate at the bottom of the underground heat exchanger pipeline, which will affect the system operation

Method used

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  • Oil return control method of direct expansion type earth source heat pump
  • Oil return control method of direct expansion type earth source heat pump

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Embodiment Construction

[0026] figure 1 is the direct expansion ground source heat pump system diagram, where A 1 、A 2 ,...,A N All are underground heat exchangers; electromagnetic valves are installed at the entrances of each underground heat exchanger, followed by B 1 , B 2 ,...,B N , each solenoid valve is connected with the controller 15, and the differential pressure sensor 16 is installed at the inlet and outlet of the underground heat exchanger, and the differential pressure sensor 16 is connected with the controller 15.

[0027] In the oil return control method of the direct expansion ground source heat pump of the present invention, under the condition that the total refrigerant flow rate is constant, the electromagnetic valves of the branch pipelines of some underground heat exchangers are closed to reduce the number of pipelines of the underground heat exchangers in actual operation. Increase the flow rate of the refrigerant, and use the high-speed flowing refrigerant to bring the lub...

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Abstract

The invention provides a method for controlling oil return of a direct expansion type earth source heat pump. The method comprises the following steps: the differential pressure between inlet and outlet of pipelines of an underground heat exchanger group of the direct expansion type earth source heat pump is monitored in real time; whether the underground heat exchanger pipeline accumulates lubricant or not can be determined by the change of the differential pressure; part of the underground pipeline is closed for a certain period in sequence, when the underground heat exchanger pipeline accumulates lubricant or the system continuously and normally operates over a preset time, thereby increasing the flow speed of freezing medium in other underground pipelines; lubricant accumulated in a buried copper tube which is blocked can be brought to a compressor by the high-speed flowing freezing medium, thereby realizing smooth oil return. The method can improve the efficiency of system oil return and the stability of system operation, avoids failures of the compressor caused by oil lack, and ensures high-efficient operation of the direct expansion type earth source heat pump system.

Description

technical field [0001] The invention relates to ground source heat pump technology, in particular to an oil return control method of a direct expansion ground source heat pump. Background technique [0002] Direct expansion ground source heat pump is an advanced technology that can more efficiently utilize low-grade heat energy in shallow surface soil. Compared with traditional ground source heat pumps, it directly charges refrigerant in the underground heat exchanger pipeline, reducing In the intermediate heat exchange link, the system efficiency is improved, and there is no danger of freezing, and there is no need to add antifreeze; at the same time, due to the reduction of intermediate heat exchange pipelines, the consumption of pipes is relatively reduced, and the amount of underground construction is also relatively reduced. Direct expansion ground source heat pumps are mainly used in small systems, so the number of buried pipes is relatively small, generally no more th...

Claims

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Application Information

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IPC IPC(8): F25B49/02F25B30/06
Inventor 张国强杨伟周晋林汉柱
Owner HUNAN UNIV
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