Series Heat Pump Control to Reduce Downstream Refrigerant Pressure
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Solution Overview
Problem
In heat pump systems where multiple heat pump devices are connected in series, the pressure of refrigerant in the heat exchanger increases as the device is located further downstream, making it difficult to reduce manufacturing costs due to the need for expensive high-pressure parts in the last heat pump device.
Innovation Solution
A control device that allocates a smaller variation amount to the most downstream heat pump device when the target temperature is exceeded, allowing for the use of less expensive parts by distributing the temperature variation across other devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the heat pump device is downsized to reduce manufacturing cost, then the device size and material cost are reduced, but the refrigerant pressure in the heat exchanger becomes higher
Solution Approach 1:
The control device dynamically adjusts the operation parameters (temperature variation amounts) of heat pump devices based on water temperature conditions. When downstream water temperature exceeds the target, the system reduces the temperature variation amount for downstream devices and increases it for upstream devices, thereby controlling refrigerant pressure within acceptable ranges even for downsized heat exchangers with smaller capacity
Solution Approach 2:
The system transitions from static heat pump device configuration to dynamic operation control. The control device continuously monitors water temperature and adjusts the temperature variation amounts allocated to each heat pump device in real-time, enabling flexible adaptation to changing operating conditions and allowing downsized devices to operate safely under controlled pressure conditions
2Stress or pressure
If expensive high-pressure parts are used in the downstream heat pump device to withstand high refrigerant pressure, then the pressure resistance is improved, but the manufacturing cost increases
Solution Approach 1:
The invention enables the use of cheaper, downsized heat exchanger parts in downstream heat pump devices by controlling their operating conditions. Instead of always using expensive high-pressure rated parts, the system allows standard or downsized parts to be used when the control device limits their temperature variation and refrigerant pressure through dynamic parameter adjustment
Solution Approach 2:
The control device changes the operating parameters (temperature variation amounts) of downstream heat pump devices based on real-time water temperature conditions. When downstream water temperature exceeds the target temperature, the system reduces the temperature variation amount for downstream devices, thereby controlling refrigerant pressure within acceptable ranges for standard or downsized heat exchangers
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
Enables the use of inexpensive parts in the heat exchanger of the furthest downstream heat pump device, facilitating downsizing and reducing manufacturing costs of the heat pump system.
Implementation Method 1
Each of the heat pump devices needs to raise the temperature of water by performing heat exchange while the water passes through the inside of the device itself
Data Source
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AI summary
A temperature variation control unit performs a control for varying the temperature of water in a facility on the basis of the amount of variation in the water temperature, the device performance, the target outlet water temperature, the measured value of the inlet water temperature, and the measured value of the outlet water temperature. A variation amount allocation determining unit determines the amount of variation allocated to a plurality of heat pump devices other than the heat pump device furthest downstream so that the amount of variation allocated to the heat pump device furthest downstream is smaller than the amount of variation during normal circumstances.