Heat source system
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Solution Overview
Problem
In existing heat source systems, sudden reductions in water flow rate and temperature can cause the heat medium to freeze, leading to the shutdown of the heat source device, which requires a significant restart time and affects operational efficiency.
Innovation Solution
A heat source system with a duplex pump configuration that includes flow control pumps and controllers, which increase the frequency of the flow control pump when the evaporating temperature drops to a threshold, preventing the heat medium from freezing and allowing continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the water flow rate is suddenly reduced due to a sudden drop in load, then the cooling capacity is reduced to match the load, but the water temperature suddenly drops causing the evaporating temperature to fall below the freezing point
Solution Approach 1:
The controller increases the frequency of the flow control pump in advance when the evaporating temperature approaches the freezing point, before actual freezing occurs. This preliminary action prevents the harmful effect of freezing while maintaining system stability and avoiding shutdown.
Solution Approach 2:
The controller continuously monitors the evaporating temperature of the load-side heat exchanger and adjusts the flow control pump frequency based on real-time temperature feedback. When the temperature drops to a predetermined threshold, the controller automatically increases pump frequency to prevent freezing, creating a closed-loop control system that maintains reliability while adapting to load changes.
2Reliability
If the heat source device is stopped to prevent freezing, then the risk of heat medium freezing is eliminated, but a significant restart time is required reducing operational efficiency
Solution Approach 1:
The flow control pump increases frequency in advance to maintain evaporating temperature above the freezing point, preventing the need for shutdown. This eliminates the restart time penalty while maintaining freezing prevention, as the system continues operating continuously with adjusted pump speed.
Solution Approach 2:
The system dynamically adjusts the flow control pump frequency based on real-time evaporating temperature conditions rather than using a static stop-start control strategy. This dynamic adjustment allows continuous operation with optimized pump speed, eliminating restart losses while maintaining temperature control.
3Extent of automation
If a system control device controls the heat source device-side water flow rate from outside the heat source device, then the entire heat source system can be controlled in an integrated manner, but the heat source device cannot be controlled on the heat source device side
Solution Approach 1:
The controller integrates both the heat source device control functions and the flow control pump control functions into a single unified control unit. This merging allows the heat source device to be controlled on the heat source device side while maintaining integrated system control, eliminating the need for separate control systems and simplifying operation.
Solution Approach 2:
The controller is designed with multi-functionality, serving both as the heat source device controller and the flow control pump controller. This universal control unit can manage the entire heat source system including refrigerant flow, heat medium flow rate, and pump frequency adjustment, providing both integrated automation and local control capability.
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
The system effectively prevents the heat medium from freezing, enabling the heat source device to continue operating stably even with sudden reductions in flow rate and temperature, thereby improving operational efficiency and reducing downtime.
Implementation Method 1
the controller increases the frequency of the flow control pump to prevent the heat medium flowing through the load-side heat exchanger from being frozen
Implementation Method 2
a load-side heat exchanger configured to cool or heat the heat medium
Data Source
Figure 1
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AI summary
Provided is a heat source system including a refrigerant circuit formed by connecting a compressor, a heat source-side heat exchanger, an expansion valve, and a load-side heat exchanger, a heat medium circuit including a flow control pump configured to pump heat medium to the load-side heat exchanger, and configured to circulate the heat medium to a load device that is provided downstream of the load-side heat exchanger, and a controller configured to control a frequency of the flow control pump. The controller is configured to increase the frequency of the flow control pump when an evaporating temperature of the load-side heat exchanger drops to a flow rate threshold.