Heat Pump Bypass Control for Compressor Discharge Temperature
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Solution Overview
Problem
Existing heat pump systems face challenges in reducing discharge temperature due to insufficient refrigerant flow capability, which can increase production costs and system dimensions, and altering refrigerant bypass amounts affects system performance negatively.
Innovation Solution
The heat pump system utilizes the first bypass pipe, originally for subcooling, to support the injection system by controlling the opening degree of the first bypass valve based on both superheated and discharge temperatures, enhancing refrigerant flow capability without increasing the second bypass pipe's thickness or number, thereby improving efficiency, reliability, and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness and/or number of the second bypass pipe is increased to improve refrigerant flow capability, then the discharge temperature can be reduced, but the production cost and system dimensions increase
Solution Approach 1:
The first bypass pipe, originally designed solely for subcooling function, is made to serve dual purposes: maintaining subcooling while supporting refrigerant injection to reduce discharge temperature. The controller enables the first bypass valve to regulate refrigerant flow into the first bypass pipe based on discharge temperature conditions, allowing this pipe to function as both a subcooling channel and an injection channel without requiring additional pipes or increasing system dimensions.
2Temperature
If the amount of refrigerant bypassing through the second bypass is increased to reduce discharge temperature, then the discharge temperature decreases, but the heat exchange performance deteriorates
Solution Approach 1:
The first bypass pipe acts as an intermediary channel that receives refrigerant from the liquid refrigerant pipe and delivers it to the low-pressure refrigerant pipe or compressor injection port. By utilizing this existing intermediary pathway for injection purposes, the system can control discharge temperature without modifying the second bypass pipe's refrigerant flow, thereby avoiding negative impacts on heat exchange performance while achieving the desired temperature reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces discharge temperature while preventing increases in production cost and system dimensions, enhancing the heat pump's efficiency, reliability, and safety by leveraging the first bypass pipe for both subcooling and injection functions.
Implementation Method 1
a refrigerant heat exchanger configured to cause a heat-exchange between refrigerant flowing in the liquid refrigerant pipe and refrigerant flowing in first bypass pipe
Implementation Method 2
The refrigerant flowing in first bypass pipe is decompressed and expanded by a first bypass valve disposed in the first bypass pipe to become cooler than the refrigerant flowing in the liquid refrigerant pipe
Implementation Method 3
the refrigerant flowing in second bypass pipe is decompressed and expanded by a second bypass valve disposed in the second bypass pipe to become cooler than the refrigerant flowing in the low-pressure refrigerant pipe
Data Source
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AI summary
Provided is a heat pump system (100) having a first bypass pipe (331) provided with first bypass valve (341) and connecting a liquid refrigerant pipe (322) and a low-pressure refrigerant pipe (324), a refrigerant heat exchanger (314) configured to cause a heat-exchange between refrigerant flowing in the liquid refrigerant pipe and refrigerant flowing in first bypass pipe, a second bypass pipe (332) provided with a second bypass valve (342) and connecting the liquid refrigerant pipe and the low-pressure refrigerant pipe, and a controller 400. The controller is configured to control opening degree of the first bypass valve based on detected superheated temperature of refrigerant flowing in the first bypass pipe, and detected discharge temperature of a compressor (311) and control opening degree of the second bypass valve based on the detected discharge temperature.