Refrigeration System COP Calculation Without Flow or Power Meters
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Solution Overview
Problem
Calculating the coefficient of performance (COP) for refrigeration systems is challenging due to the need for nonconventional sensors like power meters and flow meters, which are difficult and costly to integrate, making it hard to evaluate the system's efficiency relative to its theoretical design.
Innovation Solution
A refrigeration system with a controller that uses processor-executed instructions to calculate a weighted Carnot efficiency and coefficient of performance based on outdoor temperature, case load, defrost status, and pressure data, along with enthalpy calculations, to determine system performance indices and indicate if the system is operating below a threshold efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If nonconventional sensors like power meters and flow meters are used to calculate COP, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the COP calculation from the traditional sensor-based measurement approach and implements it through a controller that uses existing temperature and pressure sensors combined with thermodynamic property data. This removes the need for additional power meters and flow meters, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent uses a copy of thermodynamic property data (from lookup tables or equations of state) combined with measurements from existing sensors to calculate COP, rather than directly measuring power and flow with specialized sensors. This copying approach achieves accurate COP calculation without requiring complex additional sensing equipment.
2Measurement precision
If nonconventional sensors like power meters and flow meters are used to calculate COP, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the requirement for expensive power meters and flow meters from the system architecture. Instead, it extracts COP calculation capability from specialized hardware and implements it through software algorithms running on the existing controller, significantly reducing manufacturing costs while maintaining measurement precision.
Solution Approach 2:
The patent replaces expensive, complex sensors with a combination of inexpensive existing sensors (temperature and pressure sensors already present in the refrigeration system) and computational algorithms. This substitution dramatically reduces the cost of implementing COP measurement capability.
3Measurement precision
If traditional COP calculation methods are used, then efficiency evaluation is accurate, but ease of operation deteriorates due to difficult sensor integration
Solution Approach 1:
The patent makes the existing temperature and pressure sensors serve multiple functions: they not only monitor system operation but also provide data for COP calculation. This multi-functionality approach maintains accurate efficiency evaluation while eliminating the need for separate specialized sensors, greatly improving ease of operation.
Solution Approach 2:
The controller automatically performs COP calculations using data from existing sensors without requiring additional manual sensor installation or complex configuration. The system serves itself by utilizing already-present sensing capabilities for dual purposes, making the system easier to operate and deploy.
Data Source
AI summary
Systems and methods for performing dynamic coefficient of performance calculations for refrigeration systems are provided. A controller calculates a weighted Carnot efficiency of a refrigeration case based on outdoor temperature data, refrigeration case temperature data, a case load of a refrigeration case, and a case defrost status of the refrigeration case. The controller calculates a weighted coefficient of performance based on based on a refrigerant type, the case load of the refrigeration case, the case defrost status of the refrigeration case, and at least one of the of the refrigeration case temperature data and pressure data. The controller calculates a system performance index (SPI) for the refrigeration case based on the weighted Carnot efficiency of the refrigeration case and weighted actual Carnot efficiency. The controller generates, in response to the SPI being below a threshold, an output indicating that the refrigeration case is operating below a threshold efficiency.