Heat source system and control method therefor
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Solution Overview
Problem
Existing heat source systems face challenges in maintaining a stable supply water temperature when the number of operating heat source machines changes, leading to deviations from the target temperature, as existing methods either excessively lower or fail to adequately control the supply water temperature.
Innovation Solution
A heat source system that calculates a compensation temperature to maintain the supply water temperature near the target by adjusting the outlet temperature setting of operational heat source machines and setting the flow rate of added or subtracted machines, anticipating and predicting changes in supply water temperature to supplement capability shortfalls and prevent deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the set value of cold/hot water outlet temperature is excessively lowered to suppress rise in supply water temperature, then the supply water temperature becomes excessively lowered and may be separated from target supply water temperature, but if the set value is not lowered, then the supply water temperature rises excessively above target supply water temperature
Solution Approach 1:
The system performs preliminary action by changing the outlet temperature set value before the heat source machine is actually started or stopped. When a heat source machine is to be added, the outlet temperature set value is lowered in advance; when a machine is to be subtracted, the set value is raised in advance. This preliminary adjustment compensates for the temperature fluctuations that would occur during machine transitions, ensuring the supply water temperature remains close to the target temperature throughout the transition process.
2Temperature
If the flow rate of refrigerator is set higher than anticipated flow rate, then rise in supply water temperature is suppressed, but when cold water outlet setting temperature is not lowered, then supply water temperature becomes higher than target supply water temperature
Solution Approach 1:
The system applies parameter changes by dynamically adjusting both the outlet temperature set value and the flow rate of the heat source machine. When a machine is added, the outlet temperature set value is lowered and the flow rate is set higher than anticipated; when a machine is subtracted, the outlet temperature set value is raised and the flow rate is reduced. These coordinated parameter changes ensure that supply water temperature is maintained close to target while optimizing flow rate efficiency.
3Speed
If heat source machine is started immediately when capability is needed, then response time is reduced, but supply water temperature temporarily separates from target temperature during capability exercise period
Solution Approach 1:
The system performs preliminary action by adjusting the outlet temperature set value before the heat source machine starts operation. When a machine is to be added, the outlet temperature set value is lowered in advance of the machine start. This preliminary adjustment compensates for the temperature rise that would occur when the machine starts and begins exercising its capability, allowing the machine to start immediately for fast response while maintaining supply water temperature stability.
Data Source
AI summary
The purpose of the present invention is to maintain a water supply temperature close to a target water supply temperature at the time of a change in the number of heat source machines operating. A heat source system of the present invention anticipates a case where a prescribed minimum flow rate is set for heat source machines that are subject to addition or removal, and calculates, as compensation temperatures, hot and cold water outlet temperatures of the heat source machines so that the water supply temperature in such a case will match a target water supply temperature, and changes the hot and cold water outlet temperature settings of the operating heat source machines to the compensation temperatures. After that, the heat source machines that are subject to addition or removal are either started up or stopped, and the set flow rate for the heat source machines that are subject to addition or removal is set to the minimum flow rate.