Heat Pump Condensing Temperature Control for Stable Hot Water Supply
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Solution Overview
Problem
In air-conditioning and hot water supplying composite systems with a single refrigerant system, the hot water supply unit struggles to stably control water delivery temperature, especially in low-temperature ranges, and experiences a degraded coefficient of performance (COP) in high-temperature ranges due to specialized refrigerant control for air-conditioning use.
Innovation Solution
The system includes a controller with a mode switching unit that switches between a hot water supply control mode and a preheating mode, and a condensing temperature control unit that sets a target condensing temperature based on the heat medium temperature during the hot water supply control mode, allowing stable temperature control and improved COP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refrigerant control is specialized for air-conditioning use in a single refrigerant system, then the system can perform heating operation and hot water supplying operation simultaneously, but the water delivery temperature control becomes unstable in low-temperature range and COP degrades in high-temperature range
Solution Approach 1:
The patent implements dynamic control mode switching between hot water supply control mode and hot water supply preheating mode based on operational conditions. The controller dynamically adjusts the control strategy for the hot water supply unit, switching between modes where condensing temperature is determined by heat medium temperature (control mode) or fixed target condensing temperature (preheating mode), thereby adapting to varying temperature requirements and maintaining stable water delivery temperature control across different operating ranges
Solution Approach 2:
The patent changes the control parameter for condensing temperature based on the operational mode. In hot water supply control mode, the target condensing temperature is determined according to the heat medium temperature, while in preheating mode, a fixed target condensing temperature is used. This parameter change enables the system to optimize performance for different operational requirements, improving both temperature control stability and COP
2Use of energy by moving object
If the target condensing temperature is fixed for air-conditioning optimization, then the heating operation efficiency is maximized, but the hot water supply unit experiences degraded COP in high-temperature range
Solution Approach 1:
The system dynamically switches between two control modes: in hot water supply preheating mode, a fixed target condensing temperature optimizes heating operation efficiency; in hot water supply control mode, the target condensing temperature is determined according to heat medium temperature, optimizing hot water supply efficiency. This dynamic switching minimizes energy loss across different operational scenarios
Solution Approach 2:
The patent changes the target condensing temperature parameter based on the active control mode. When in preheating mode, the fixed target condensing temperature maximizes heating efficiency. When in control mode, the heat medium temperature-dependent target condensing temperature maximizes hot water supply efficiency, thereby reducing overall energy loss
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 enables the hot water supply unit to stably control water delivery temperatures and enhances the system's coefficient of performance (COP) by adjusting the target condensing temperature according to the heat medium temperature, addressing the previous instability and performance degradation issues.
Implementation Method 1
a heat pump cycle and configured to exchange heating energy with a heat source (air or water) and supply the heating energy
Implementation Method 2
a hot water supply unit having a hot water supply-side heat exchanger and a hot water supply-side expansion device
Implementation Method 3
a heat source unit including a compressor and a heat source-side heat exchanger
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
An air-conditioning and hot water supplying composite system includes a heat source unit including a compressor and a heat source-side heat exchanger, an indoor unit connected to the heat source unit and including an indoor heat exchanger and an indoor expansion device, the indoor unit being configured to perform a heating operation, a hot water supply unit connected to the heat source unit and including a hot water supply-side heat exchanger and a hot water supply-side expansion device, the hot water supply unit being configured to perform a hot water supplying operation, and a controller that controls the heat source unit. The controller includes a mode switching unit that switches a control mode of the air-conditioning and hot water supplying composite system between a hot water supply control mode in which the hot water supplying operation is primarily performed and a hot water supply preheating mode in which the heating operation is primarily performed, and a condensing temperature control unit that determines a target condensing temperature depending on the control mode. The condensing temperature control unit determines the target condensing temperature according to a temperature of a heat medium subjected to heat exchange by the hot water supply unit, in the hot water supply control mode.