Centrifugal Chiller COP Evaluation Using Loss Correction Factors
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Solution Overview
Problem
The existing methods for calculating the design COP of centrifugal chillers are impractical due to the need for iterative calculations and large amounts of data, making it difficult to handle in devices with limited throughput, such as control panels, and are not efficient in compensating for varying operating conditions.
Innovation Solution
A performance evaluation system that uses a data acquisition section, storage section, and computing section to estimate design COP using a simplified computational formula incorporating correction values for losses, including a first correction value based on the load factor and a second correction value based on temperature differences, allowing for iterative calculation and precise compensation for heat loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If iterative calculation of design COP is performed using conventional methods, then measurement precision of chiller performance is improved, but device complexity and computational burden increase significantly
Solution Approach 1:
The patent transforms the complex iterative calculation problem into a direct calculation by changing the mathematical parameters from requiring full thermodynamic property iterations to using pre-determined correction values based on temperature differences and load factors. This allows the control panel to calculate design COP without excessive computational burden while maintaining accuracy.
Solution Approach 2:
The patent performs preliminary calculations of correction values during the design phase or pre-processing stage, storing these correction factors for direct application during operation. This preliminary action eliminates the need for complex iterative calculations during real-time performance evaluation, reducing computational complexity while preserving measurement precision.
2Measurement precision
If conventional design COP calculation methods are used, then measurement precision is improved, but productivity of performance evaluation decreases due to extensive data processing requirements
Solution Approach 1:
The patent extracts only the essential parameters needed for design COP calculation (temperature differences and load factor) from the complete set of thermodynamic data, eliminating unnecessary data processing steps. This extraction approach maintains calculation accuracy while significantly improving productivity by reducing data processing requirements.
Solution Approach 2:
The patent uses pre-calculated correction values that replicate the results of complex thermodynamic calculations without requiring the full computational process. These copied correction factors allow rapid performance evaluation while maintaining the precision equivalent to detailed iterative calculations.
3Measurement precision
If comprehensive thermodynamic calculations are performed, then measurement precision of design COP is improved, but loss of time increases due to extensive computational requirements
Solution Approach 1:
The patent changes the calculation parameters from requiring complete thermodynamic property iterations to using simplified parameters (temperature difference and load factor) with pre-determined correction values. This parameter transformation maintains measurement precision while dramatically reducing calculation time for performance evaluation.
4Measurement precision
If detailed performance analysis is conducted, then measurement precision is improved, but ease of operation decreases due to complexity of data input and processing
Solution Approach 1:
The patent extracts only the essential operational parameters (cooling water temperature, chilled water temperature, and load factor) needed for design COP calculation, eliminating the need for operators to input and process extensive thermodynamic data. This extraction simplifies operation while maintaining measurement precision through the use of correction values.
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
Enables efficient iterative computation of design COP even in devices with limited throughput, providing precise calculations and eliminating errors due to varying operating conditions, thus improving the performance evaluation of centrifugal chillers.
Implementation Method 1
a design COP estimation formula which adds correction values corresponding to losses occurring in an actual environment to a computational formula for ideal actual-machine COP expressed using COP characteristics of a reverse Carnot cycle
Data Source
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AI summary
Design COP is iteratively computed. Provided is a centrifugal chiller performance evaluation system including a data acquisition section (101) for acquiring operating data from a centrifugal chiller as input data; a storage section (102) storing a design COP estimation formula obtained by adding correction values corresponding to losses occurring in an actual environment to a computational formula for ideal actual-machine COP expressed using COP characteristics of a reverse Carnot cycle; and a computing section (103) for estimating a design COP at a current operating point using the operating data acquired by the data acquisition section (101) and the design COP estimation formula stored in the storage section (102). The correction values include a first correction value calculated from a first computational formula including the load factor of the centrifugal chiller as a variable and a second correction value calculated from a second computational formula including a difference between cooling water outlet temperature and chilled water outlet temperature as a variable. The second correction value contains an offset from the first correction value depending on cooling water inlet temperature.