Multi-Unit Heat Pump Pressure Control for Mixed Temperature Loads
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Solution Overview
Problem
Heat pump systems operating with multiple usage units connected to a single heat source face challenges in optimizing refrigerant supply to individual units with different temperature requirements, leading to inefficient operation and potential overheating or underheating.
Innovation Solution
The system employs a variable-capacity compressor and heat exchangers to control discharge pressure and refrigerant flow rates based on target values determined by the highest required temperature among connected units, ensuring optimal refrigerant distribution and maintaining consistent subcooling across all units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single heat source supplies refrigerant to multiple usage units with different temperature requirements, then the system can serve multiple applications, but it becomes difficult to optimize refrigerant supply to each individual unit
Solution Approach 1:
The patent applies local quality by determining individual target values for each usage unit based on their specific temperature requirements and heat exchange capacities. Each usage unit receives customized refrigerant control parameters (target superheat values) tailored to its local conditions, allowing optimal performance for floor heating, hot water supply, and air conditioning applications simultaneously
Solution Approach 2:
The system dynamically adjusts the target superheat values for each usage unit based on real-time operating conditions. The control unit modifies refrigerant flow targets according to the specific application (floor heating vs. hot water vs. air conditioning) and current system state, enabling adaptive optimization rather than fixed parameters
2Device complexity
If the compressor operates at fixed capacity, then the system structure is simple, but it cannot efficiently meet varying temperature demands of different usage units
Solution Approach 1:
The patent employs a variable-capacity compressor that dynamically adjusts its operating capacity based on the aggregate heat exchange requirements of all connected usage units. The control unit calculates the total heating or cooling demand and modulates compressor speed accordingly, enabling efficient meeting of varying temperature demands while maintaining system simplicity
3Productivity
If refrigerant flow is optimized for one usage unit, then that unit operates efficiently, but other usage units may experience overheating or underheating
Solution Approach 1:
The patent segments the refrigerant control into individual pathways for each usage unit, with separate target superheat values calculated for each unit based on its specific requirements. The control unit independently manages refrigerant allocation to each unit while coordinating overall system operation, ensuring each unit receives optimized refrigerant flow without compromising others
Solution Approach 2:
The system implements feedback control by continuously monitoring actual superheat conditions at each usage unit and adjusting refrigerant flow targets accordingly. The control unit compares measured temperatures against calculated target values and modifies compressor capacity and expansion valve positions to maintain temperature consistency across all units
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 approach allows for efficient refrigerant management, ensuring that all connected units receive the necessary temperature, preventing overheating and underheating, and optimizing the system's performance across various applications.
Implementation Method 1
a heat-source-side heat exchanger functioning as an evaporator for a refrigerant
Implementation Method 2
usage-side heat exchangers that function as radiators for the refrigerant
Implementation Method 3
capable of heating an aqueous medium through radiation by the refrigerant
Implementation Method 4
a variable-capacity compressor
Data Source
AI summary
A heat pump system includes a heat source unit having a variable-capacity compressor and a heat-source-side heat exchanger that functions as an evaporator for a refrigerant, and a plurality of usage units connected to the heat source unit and having usage-side heat exchangers that function as radiators for the refrigerant. The operating capacity of the compressor is controlled to bring the discharge pressure of the compressor, or a state quantity equivalent to the discharge pressure, to a first target value. The first target value is determined based on an equivalent target value equivalent to a usage temperature required in individual usage units.