Apparatus and method for evaluating performance of centrifugal chiller
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Solution Overview
Problem
Existing methods for evaluating the performance of centrifugal chillers, such as those described in PTL 1, inaccurately account for losses in components like heat exchangers by using constant values for loss-equivalent temperature differences, which reduces the accuracy of calculated target COP.
Innovation Solution
An apparatus and method that calculate the target COP by incorporating heat exchange loss of the evaporator as a correction term, using a function with the load factor as a parameter, to improve accuracy, and also consider mechanical losses due to the compressor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant value is used for loss-equivalent temperature difference of heat exchangers, then the calculation is simple, but the accuracy of target COP calculation deteriorates
Solution Approach 1:
The patent transforms the static constant value approach into a dynamic variable approach by introducing a function that calculates the loss-equivalent temperature difference based on the load factor. This allows the temperature difference to vary with operating conditions, improving accuracy while maintaining calculation simplicity through the use of a standardized function form.
Solution Approach 2:
The patent changes the parameter from a fixed constant to a variable dependent on the load factor. By expressing the loss-equivalent temperature difference as a function of the load factor, the calculation adapts to different operating conditions, thereby improving target COP calculation accuracy without significantly increasing complexity.
2Measurement precision
If the heat exchange loss of evaporator is expressed as a function with load factor as parameter, then the accuracy of target COP calculation is improved, but the device complexity increases
Solution Approach 1:
The patent introduces a functional relationship between the loss-equivalent temperature difference and the load factor. This parameter change allows the calculation to reflect actual operating conditions, improving accuracy. The complexity increase is managed by using a standardized function form that can be easily implemented.
Solution Approach 2:
The patent makes the loss-equivalent temperature difference dynamic by expressing it as a function of the load factor. This dynamic approach allows the calculation to adapt to varying operating conditions, improving accuracy. The implementation remains straightforward by using a well-defined functional relationship.
Data Source
AI summary
A calculating section 103 calculates a target COP that is a maximum COP that the centrifugal chiller can achieve using an arithmetic expression in which an actual device loss is given as a correction term to an expression that represents a COP characteristic under an ideal lossless environment. Since the arithmetic expression for calculating the target COP includes the heat exchange loss of the evaporator as a correction term, the heat exchange loss being calculated using a function having a load factor as a parameter, the heat exchange loss of the evaporator is reflected in the target COP.