Heat Source Machine Start-Stop Control to Prevent Frequent Cycling
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Solution Overview
Problem
Existing methods for controlling the number of heat source machines in a heat source system often result in frequent start and stop cycles due to narrow load factor ranges, leading to inefficient operation.
Innovation Solution
A number-of-machines control device that uses specific basic conditions for increasing or decreasing the number of machines based on refrigeration load and required load, with additional checks to prevent erroneous determinations and noise influences, including forced load factors to ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the load factor range is set narrowly to maintain efficient operation, then the COP is maintained above a predetermined value, but the number of heat source machines frequently starts and stops
Solution Approach 1:
The control device performs preliminary evaluation by calculating the load factor range under the assumption that the number of heat source machines is increased or decreased by one, before actually executing the start or stop command. This preliminary calculation prevents frequent and unnecessary machine start/stop operations by anticipating the outcome of number-of-machines changes.
Solution Approach 2:
The control device dynamically adjusts the number of heat source machines based on real-time load factor calculations. It determines an appropriate number of machines by evaluating whether increasing or decreasing the machine count maintains the load factor within the efficient range, thereby dynamically optimizing both energy efficiency and operational stability.
2Stability of the object's composition
If the number of heat source machines is increased to prevent exceeding the upper limit of the load factor range, then the load factor is maintained below the upper limit, but the number of machines increases unnecessarily causing frequent start/stop cycles
Solution Approach 1:
The control device calculates the load factor range in advance by assuming an increase in the number of heat source machines by one, and determines whether this preliminary calculation keeps the load factor within the efficient range. This prevents unnecessary machine starts by evaluating the outcome before execution.
Solution Approach 2:
The control device continuously monitors the actual load factor and compares it with the upper limit of the efficient range. Based on this feedback, it determines whether increasing the number of machines is necessary, thereby maintaining load factor stability while avoiding unnecessary machine additions.
3Loss of energy
If the number of heat source machines is decreased to maintain efficient operation below the lower limit of the load factor range, then the load factor is maintained above the lower limit, but the number of machines decreases unnecessarily causing frequent start/stop cycles
Solution Approach 1:
The control device performs preliminary evaluation by calculating the load factor range under the assumption that the number of heat source machines is decreased by one, before actually executing the stop command. This preliminary calculation prevents frequent and unnecessary machine start/stop operations.
Solution Approach 2:
The control device monitors the actual load factor and compares it with the lower limit of the efficient range. Based on this feedback, it determines whether decreasing the number of machines is appropriate, thereby maintaining energy efficiency while avoiding unnecessary machine reductions that would cause operational instability.
Data Source
AI summary
A control device and method for preventing the start and stop of heat source machines from being frequently repeated. The control device determining whether or not basic conditions for decreasing the number of machines are satisfied when the number of currently operating machines is increased by one is determined if a current operational status satisfies basic conditions for increasing the number of machines, and one heat source machine is started if it is determined that the basic conditions for decreasing the number of machines are not satisfied, and determining whether or not the basic conditions for increasing the number of machines are satisfied when the number of currently operating machines is decreased by one are satisfied if a current operational status satisfies the basic conditions for decreasing the number of machines, and one heat source machine is stopped if it is determined that the basic conditions for increasing the number of machines are not satisfied.