Low-temperature heat pump water machine enhanced vapor injection system and control method thereof

Abstract

The invention discloses a low-temperature heat pump water machine enhanced vapor injection system. The system comprises a compressor, a four-way valve, an indoor heat exchanger, an outdoor heat exchanger and a water side heat exchanger, a main path expansion valve is arranged at the position, between the outdoor heat exchanger and the water side heat exchanger, of a flow path pipeline, and an auxiliary path pipeline is further included. One end of the auxiliary path pipeline extends to penetrate through the outdoor heat exchanger and then is connected to the position, between the outdoor heatexchanger and the main path expansion valve, of the flow path pipeline in a bypass manner, the other end of the auxiliary path pipeline is connected to an input port of the compressor, and the position, between the outdoor heat exchanger and a bypass position, of the auxiliary path pipeline is provided with an auxiliary path expansion valve; and an exhaust temperature sensor used for detecting andobtaining the exhaust temperature TP in real time is arranged at the position, between an output port of the compressor and the four-way valve, of the flow path pipeline, and therefore whether interference adjustment is conducted on the system or not is determined on the basis of the detected and obtained exhaust temperature TP under the low-temperature working condition. When interference adjustment needs to be carried out on the system, the opening degree of the main path expansion valve and the opening degree of the auxiliary path expansion valve are correspondingly adjusted based on the exhaust temperature TP obtained through detection and the calculated exhaust superheat degree SH.

Description

technical field [0001] The invention relates to the technical field of heat pump air-conditioning systems, in particular to a low-temperature heat pump water machine air injection enthalpy increasing system and a control method thereof. Background technique [0002] When the existing low-temperature air-source heat pump (chiller) unit operates under the conditions of low ambient temperature and high water temperature, the exhaust temperature of the unit is likely to be too high under normal logic adjustment (TP≥108°C), and additional The exhaust protection logic intervenes to reduce the exhaust temperature when the unit is running. The conventional solution is to force the unit to adjust to a fixed valve opening after the unit reaches the set exhaust temperature. After the logic, the exhaust temperature will be too high again, and then the forced adjustment will be performed, and so on. The disadvantages of this exhaust temperature protection logic are: [0003] 1. After r...

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Problems solved by technology

The disadvantages of this exhaust temperature protection logic are:

[0003] 1. After reaching the set exhaust temperature, the exhaust temperature of the unit will always fluctuate with the frequent adjustment of the valve opening (the temperature curve is jagged), which is not conducive to the stable control operation of the unit;

[0004] 2. The setting of the fixed valve opening does not have the applicability of various models, and each model needs to re-match the fixed valve opening; if the consistency of the production process in the workshop is poor, the fixed valve opening is only applicable to Units that are consistent with the model used to match them have uncontrolled hidden dangers

[0005] The technical reasons that lead to the problem: 1. For the jet booster model, it is necessary to control two electronic expansion valves in the main circuit and the auxiliary circuit at the same time, and the control logic is complicated; 2. In the low-temperature heating condition, the exhaust temperature of the unit reaches a higher setting When the temperature is fixed, the control logic of the opening of the main and auxiliary valves is different from the normal operation control logic of the unit, and it is more complicated to formulate the logic of the unit's intelligent exhaust control

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