Method for operating a heat pump
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional reversible air/water heat pumps suffer from reduced efficiency when switching between heating and cooling modes due to the reversal of the refrigerant circuit, which changes the direction of flow through the heat exchanger, turning a counterflow heat exchanger into a cocurrent one with reduced mean temperature difference and coefficient of performance.
Innovation Solution
The method employs two switching valves to maintain countercurrent operation of the heat exchangers during both heating and cooling modes, ensuring consistent refrigerant flow direction through the heat exchangers, thereby maintaining optimal performance in both operating modes by coupling the compressor, heat exchangers, and expansion valve in parallel between the switching valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refrigeration circuit is reversed to switch between heating and cooling modes, then the heat pump can provide both heating and cooling functions, but the direction of flow through the heat exchanger changes, turning a counterflow heat exchanger into a cocurrent one, which reduces heat transfer efficiency and coefficient of performance
Solution Approach 1:
The heat exchanger is divided into multiple independent flow circuits (first flow circuit and second flow circuit) that can be selectively activated. By segmenting the flow paths and using switching valves to control which circuit is active, the system maintains counterflow configuration in both heating and cooling modes, preventing the degradation to cocurrent flow that would reduce heat transfer efficiency.
Solution Approach 2:
The system dynamically switches between different flow circuits based on operating mode (heating or cooling) while maintaining the counterflow configuration. The switching valves enable the system to adapt the refrigerant flow path in real-time, ensuring that the heat exchanger always operates in the more efficient counterflow mode rather than being fixed in a single configuration that would become suboptimal when mode changes.
2Adaptability or versatility
If the refrigeration circuit is reversed for mode switching, then both heating and cooling operations are enabled, but the mean temperature difference between refrigerant and water or air increases, reducing the coefficient of performance
Solution Approach 1:
By segmenting the heat exchanger into multiple flow circuits with independent refrigerant flow paths, the system can maintain optimal counterflow configuration in each circuit regardless of the overall operating mode. This segmentation allows the refrigerant and water/air flows to consistently move in opposite directions, preserving the smaller mean temperature difference and higher coefficient of performance in both heating and cooling operations.
Solution Approach 2:
Switching valves act as intermediaries that control and redirect refrigerant flow between different circuits based on the desired operating mode. These valves enable the system to maintain the efficient counterflow configuration by selectively connecting the refrigerant flow through the appropriate circuit, preventing the automatic transition to cocurrent flow that would increase the mean temperature difference and reduce performance.
3Ease of operation
If conventional single switching valve configuration is used, then mode switching is possible, but optimal performance cannot be achieved in both heating and cooling modes simultaneously
Solution Approach 1:
The switching system is segmented into multiple valves (first switching valve and second switching valve) that control different flow circuits independently. This segmentation allows precise control over refrigerant flow paths in both heating and cooling modes, ensuring that the heat exchanger maintains counterflow configuration in each mode and achieving optimal performance consistency across both operating conditions.
Solution Approach 2:
The multiple flow circuits are designed to be universally applicable to both heating and cooling operations. Each circuit can function effectively in either mode, and the switching valves enable seamless transition between modes while maintaining the efficient counterflow configuration. This multi-functionality ensures consistent optimal performance regardless of the operating mode.
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 enhances heat transfer efficiency in both heating and cooling modes by maintaining countercurrent flow, optimizing the coefficient of performance and ensuring effective operation in either mode without sacrificing performance.
Implementation Method 1
The refrigerant vapor is compressed by the heat pump's compressor so that it can then be condensed again in the heat pump's condenser
Implementation Method 2
The provision of thermal heat in heat pumps takes place through the condensation of refrigerant under high pressure and thus at high temperature, while the heat is given off to a heat transfer medium, for example heating water
Implementation Method 3
The liquefied refrigerant is then expanded in a throttle element, for example an expansion valve, and then evaporates in the evaporator of the heat pump
Implementation Method 4
the refrigerant vapor is compressed by the heat pump's compressor so that it can then be condensed again in the heat pump's condenser... evaporates in the evaporator of the heat pump, absorbing ambient heat
Implementation Method 5
The direction of flow of the refrigerant through the second heat exchanger to which air is applied and the direction of flow of the refrigerant through the first heat exchanger through which water flows is the same both in the first heating mode and in the second cooling mode. The provision of the two switching valves means that the second heat exchanger, to which air is applied, and the first heat exchanger, through which water flows, are operated in countercurrent both during heating and during cooling.
Data Source
Figure 1~3
AI summary
The device has a pair of change over valves (50, 60) arranged in such a manner that a compressor (10), a condenser (20), an expansion valve (40) and an evaporator (30) are respectively coupled with the change over valves at a pair of ends. The change over valves are a four or two way-change over valve and connected in such a manner that the condenser is coupled with the compressor at one end and with the expansion valve at another end when an operating mode is activated.