Heat Pump COP Calculation Using Three Refrigerant Temperatures
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Solution Overview
Problem
Existing methods for determining the coefficient of performance (COP) of refrigeration machines are costly due to the use of multiple sensors and electricity meters, which are expensive and unnecessary for calculating the COP effectively.
Innovation Solution
A method using exactly three temperature sensors arranged in the refrigerant circuit to measure temperatures at specific points, calculating enthalpies and pressures, and determining the COP from these values without the need for additional sensors or an electricity meter, relying on known thermodynamic properties of the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors (pressure sensors, temperature sensors) and electricity meters are used to determine COP, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts only the essential temperature measurements needed for COP determination, eliminating unnecessary pressure sensors and electricity meters. By focusing on the three critical temperature points (evaporator outlet, condenser outlet, expansion valve outlet), the method achieves accurate COP calculation with minimal sensors.
Solution Approach 2:
The invention replaces expensive pressure sensors and electricity meters with simpler, cheaper temperature sensors. The method uses readily available temperature sensing technology rather than costly measurement devices, significantly reducing system cost while maintaining measurement precision.
2Measurement precision
If expensive electricity meters and pressure sensors are used, then COP determination accuracy is improved, but cost increases
Solution Approach 1:
The invention replaces expensive pressure sensors and electricity meters with simpler, cheaper temperature sensors. The method uses readily available temperature sensing technology rather than costly measurement devices, significantly reducing system cost while maintaining measurement precision.
Solution Approach 2:
The invention uses temperature measurements as a substitute (copy) for direct pressure and power measurements. By calculating enthalpies from temperature data and deriving COP from these calculations, the method avoids the need for expensive direct measurement devices.
3Ease of manufacture
If three temperature sensors are used to measure refrigerant temperatures at specific points, then COP can be determined with minimal expense, but measurement precision may be reduced compared to using multiple sensor types
Solution Approach 1:
The invention changes the measurement parameter from pressure and power (requiring expensive sensors) to temperature (measurable with cheap sensors). By measuring temperatures at three strategic points and calculating enthalpies and COP from these temperature values, the method achieves cost-effective precision.
Solution Approach 2:
The invention uses temperature as an intermediary parameter to indirectly determine COP without directly measuring pressure or power. The temperature measurements serve as a mediator that, when processed through thermodynamic calculations, yields accurate COP values without requiring expensive direct measurement devices.
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
This approach reduces costs by minimizing the number of sensors required and eliminates the need for expensive equipment, enabling efficient determination of the refrigeration machine's performance with minimal expense.
Implementation Method 1
using exactly three temperature sensors, which are arranged in the cycle, determined three temperatures of the refrigerant
Implementation Method 2
The enthalpies and pressures of the circuit are calculated from the refrigerant temperatures determined
Implementation Method 3
the coefficient of performance of the refrigerating machine is determined from the quotient of the calculated heat output and the calculated electrical power consumption
Data Source
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AI summary
The present invention relates to a method for determining the coefficient of performance of a refrigerating machine, in particular a heat pump, which includes a closed circuit containing a refrigerant, in which an evaporator, a compressor, a condenser and an expansion valve are arranged. In the method, at least three temperatures of the refrigerant are determined with the aid of temperature sensors arranged in the circuit. Alternatively, at least two temperatures and at least one pressure of the refrigerant are determined with the aid of sensors arranged in the circuit. The enthalpies of the circuit and from this the heating capacity and the consumed electrical power of the refrigerating machine are calculated from the determined refrigerant temperatures or pressures in order to determine the coefficient of performance of the refrigerating machine from the quotient of the calculated heating capacity and the calculated consumed electrical power. The invention also relates to a refrigerating machine for carrying out such a method.