Dual-Cycle Heat Pump Control for Simultaneous Cooling and Heating
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Solution Overview
Problem
Conventional heat pump systems face inefficiencies when performing simultaneous cooling and heating operations, particularly under low outside air temperatures, as they struggle to balance heat load and maintain optimal condensing temperatures, leading to increased power consumption and reduced operating efficiency.
Innovation Solution
The system employs a dual refrigeration cycle with a heat-source-side refrigerant circuit and usage-side refrigerant circuits, allowing the usage-side heat exchangers to function as both evaporators and radiators, and controlling the heat-source-side condensing temperature to below 40°C, even at low outside air temperatures, to balance heat load and reduce compressor power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the heat pump system uses multiple heat-source-side heat exchangers to balance heat load during simultaneous cooling and heating operations, then the heat load balancing capability is improved, but the compressor operating capacity increases and power consumption rises
Solution Approach 1:
The system divides the heat source functions into separate components: heat-source-side heat exchangers dedicated to heat radiation and usage-side heat exchangers dedicated to evaporation. This segmentation allows independent optimization of each function, enabling the compressor to operate at lower capacity while maintaining effective heat load balancing through the coordinated operation of multiple heat-source-side heat exchangers.
Solution Approach 2:
The usage-side heat exchangers act as intermediaries between the heat-source-side refrigerant circuit and the aqueous medium. They receive refrigerant from the heat-source-side circuit and perform evaporation to cool the aqueous medium, while the heat-source-side heat exchangers handle heat radiation to the atmosphere. This intermediary arrangement decouples the heat radiation function from the evaporation function, allowing the compressor to operate more efficiently.
2Reliability
If the condensing temperature is maintained at 50°C or higher to ensure heating operation effectiveness, then the heating performance is improved, but the heat radiation capability increases excessively under low outside air temperature conditions
Solution Approach 1:
The system separates the heating function from the heat radiation function. Heating effectiveness is ensured by maintaining proper condensing temperature in the heat-source-side heat exchangers, while the usage-side heat exchangers handle evaporation independently. This segmentation prevents excessive heat radiation loss under low outside air temperature conditions while maintaining reliable heating operation.
Solution Approach 2:
Different temperature conditions are applied to different parts of the system: the heat-source-side heat exchangers maintain condensing temperature of 50°C or higher for reliable heating, while the usage-side heat exchangers operate at lower evaporation temperatures appropriate for cooling the aqueous medium. This local quality differentiation optimizes both heating effectiveness and energy efficiency.
3Adaptability or versatility
If the heat pump system operates with both cooling and heating functions simultaneously using shared heat exchangers, then the system versatility is improved, but the operating efficiency decreases due to heat load balancing difficulties
Solution Approach 1:
The system achieves simultaneous cooling and heating by segmenting the heat exchanger functions: heat-source-side heat exchangers dedicated to heat radiation and usage-side heat exchangers dedicated to evaporation. This segmentation eliminates the heat load balancing difficulties inherent in shared heat exchanger configurations while maintaining full versatility for simultaneous cooling and heating operations.
Solution Approach 2:
The usage-side heat exchangers serve multiple functions: they act as evaporators for cooling the aqueous medium and as heat radiators for the heat-source-side refrigerant circuit. This multi-functionality enables the system to perform simultaneous cooling and heating operations efficiently without requiring separate dedicated exchangers for each function.
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 enables efficient simultaneous cooling and heating operations by reducing the heat radiation capability of heat-source-side heat exchangers, improving load balancing, and minimizing power consumption, thus enhancing overall system efficiency.
Implementation Method 1
heat exchange between the refrigerant and the aqueous medium
Implementation Method 2
the usage-side heat exchangers function as evaporators of the usage-side refrigerant
Implementation Method 3
the usage-side heat exchangers function as radiators of the heat-source-side refrigerant
Implementation Method 4
a heat-source-side compressor for compressing a heat-source-side refrigerant
Data Source
AI summary
A heat pump system includes a heat-source-side refrigerant circuit and a controller. The heat-source-side refrigerant circuit has a plurality of usage units having usage-side heat exchangers. The plurality of usage units are connected to a heat source unit having a plurality of heat-source-side heat exchangers and a heat-source-side compressor configured to compress a heat-source-side refrigerant. The controller causes the plurality of heat-source-side heat exchangers to function as evaporators and radiators of heat-source-side refrigerant to perform an air-cooling operation and an air-warming operation using an aqueous medium. The heat pump system operates so that the heat-source-side condensing temperature is below 40° C. in the case that an outside air temperature is 25° C. or lower and the cooling and heating operations coexist.