Differences between COP (Coefficient of Performance) and Efficiency-
| Criteria |
COP (Coefficient of Performance) |
Efficiency |
| Definition |
COP is a ratio of output power to input power, commonly used in the HVAC industry. |
Efficiency is a ratio of output energy to input energy, used in various applications. |
| Calculation |
COP = Desire Effect / Work Input |
Efficiency = Output Energy / Input Energy |
| Units |
Dimensionless (no unit of measurement) |
Usually expressed as a percentage or decimal |
| Range |
Greater than or equal to 1 |
Between 0 and 1 |
| Significance |
Higher COP means greater efficiency, with a perfect system having a COP of infinity. |
Higher efficiency means less wasted energy, with a perfect system having an efficiency of 1. |
| Examples |
Air conditioning, heat pumps, refrigerators |
LEDs, solar panels, electric vehicles |
| Use |
COP is commonly used in the HVAC industry for refrigeration systems. |
Efficiency is used in various applications for measuring energy efficiency. |
| Impact of Load |
COP changes with load variations, meaning it is lower at lower loads and higher at higher loads. |
Efficiency remains relatively stable regardless of load variations. |
| Impact of Temperature |
COP changes with temperature variations, meaning it is lower at higher temperatures and higher at lower temperatures. |
Efficiency remains relatively stable regardless of temperature variations. |
| Conversion |
COP can be converted to efficiency by dividing the COP by (COP + 1). |
Efficiency cannot be converted to COP. |
The key differences between COP and efficiency are in their definitions, calculations, units, range, significance, examples, and usage.
The HVAC industry primarily uses COP to measure the performance of refrigeration systems, while various applications use efficiency as a more general measure of energy efficiency.COP is always greater than or equal to 1, while efficiency is always between 0 and 1.
A higher COP indicates greater efficiency, while a higher efficiency indicates less wasted energy. Load and temperature variations affect both COP and efficiency, but in different ways. It is possible to convert COP to efficiency, but the reverse is not possible.
Questions Related with COP & Efficiency with Solution-
1. What is the Relation between COP and Efficiency?
Answer-COP (Coefficient of Performance) and efficiency are both measures of the performance of a system, but they are not the same thing.
The performance of refrigeration and air conditioning systems is typically measured using COP, which is defined as the ratio of the heat removed from the cooled space to the energy consumed by the system.
A higher COP indicates that the system is more efficient at removing heat from the cooled space.
Efficiency, on the other hand, is a more general measure of the performance of a system, and is defined as the ratio of the useful output of a system to the input required to achieve that output.
This can be applied to a wide range of systems, from engines and motors to solar panels and lighting systems.
In some cases, COP and efficiency may be directly related. For example, in a heat pump, the COP is equal to the ratio of the heat output to the electrical input, and a higher COP indicates a more efficient system. However, in other cases, such as a combustion engine, the relationship between COP and efficiency is more complex and may depend on a variety of factors, including the specific operating conditions of the system.
2. Why COP is Greater Than 1?
Answer-
The COP (Coefficient of Performance) of a system exceeds 1 because it indicates the proportion of energy that the system moves or transfers compared to the energy input to the system.
The COP in refrigeration and air conditioning systems is defined as the proportion of heat that the system removes from the cooled space to the energy consumed by the system.
This means that the COP represents the efficiency of the system in moving heat from a cooler space to a warmer space. A COP of 1 would mean that the system is just able to move the same amount of energy as it consumes, but not more. A COP greater than 1 means that the system is able to move more energy than it consumes, which indicates that it is more efficient in its operation.
It is important to note that the COP is dependent on the specific conditions and components of the system, and may vary based on factors such as temperature, pressure, and the type of refrigerant used.
3. How do you Calculate COP from Efficiency?
Answer-
It is not possible to directly calculate COP (Coefficient of Performance) from efficiency, as they are different measures of system performance. However, it is possible to calculate one from the other if certain additional information is available.
To calculate COP from efficiency, you would need to know the specific heat transfer or energy transfer rates of the system. In refrigeration or air conditioning systems, the COP is calculated as the ratio of heat removed from the cooled space to energy consumed by the system, usually in watts or BTUs per hour.
The system efficiency can be determined by calculating the ratio of output energy (heat removed) to input energy (energy consumed), usually as a percentage.
If you have the efficiency of the system and the energy consumption of the system, you can calculate the COP by dividing the efficiency by the ratio of the energy transfer rate to the electrical energy input. This calculation will give you the COP at a specific set of operating conditions, which may change depending on factors such as temperature, pressure, and the type of refrigerant used.
4. What is the relation between thermal efficiency and coefficient of performance?
Answer-
While both thermal efficiency and COP measure system performance, they evaluate different types of systems.
Thermal efficiency, which is the ratio of work output to heat input, is typically used to evaluate heat engines, such as combustion engines.
COP, which is the ratio of heat moved by the system to work input, is commonly used to evaluate refrigeration and heat pump systems.
While both thermal efficiency and COP are efficiency measures, they are calculated differently and have no direct relation.
5. What is the relation between efficiency and COP of heat engine?
Answer-
The relationship between efficiency and COP (Coefficient of Performance) of a heat engine is indirect and depends on the specific operating conditions of the system.
The efficiency of a heat engine is the ratio of the useful work output to the heat input, and is typically expressed as a percentage.
Heat engines are typically designed to produce work, not move heat, which is why the COP is not usually used as a performance metric for heat engines.
However, it is possible to calculate the COP of a heat engine if you have information about its thermal efficiency and the temperature of the heat source and heat sink. The COP of a heat engine can be expressed as the ratio of the heat moved from the heat source to the heat sink to the work input.
In general, a higher thermal efficiency of a heat engine would indicate a more efficient conversion of heat into useful work, but this does not necessarily mean that the COP of the engine would be higher. The COP of a heat engine depends on the temperature difference between the heat source and heat sink, and the specific design and operating conditions of the engine.
Q.6 What does COP mean in efficiency?
Answer- It is the ratio of desire effect to work input, please note higher COP means low operating cost.
Q.7 What is maximum COP?
Answer- Sometimes in competitive exams question you will get when you will see values given in heat as well as in temperature, when it is asking to find out maximum COP then you will use temperature way to find out COP.
Q.8 Why is it called COP and not efficiency?
Answer- COP is greater than 1 but efficiency which is impossible to get, COP term is used in case of reversed direction cycle means anti-clock wise direction cycle but in case of efficiency it is used in click direction cycle.
Q.9 What does COP mean in efficiency?
Answer- Simply you can say that there is relation between both but it differs machine to machine like for Heat pump COP and efficiency relation is different than relation between COP and efficiency for refrigerator, we can easily get by using below relation-
1 + COPR = COPHP = 1/ηHE
Q.10 How is COP related to efficiency?
Answer- Well it is different for different cases but if we want to understand it from a simple single relation then we can easily related between heat engine, heat pump and refrigerator with the below equation-
1 + COPR = COPHP = 1/ηHE
Q.11 What is the formula for refrigeration efficiency?
Answer- In case of refrigeration cycle we used COP not efficiency, here is the formula for finding out COP = Desire effect/Work Input.
Q.12 COP and efficiency difference in refrigeration?
Answer- COP is find out in case of refrigeration system but efficiency is find out in case thermodynamics. In both subjects refrigeration cycles work in the anti clock wise direction but in case of thermodynamics, cycles work in the clockwise direction.
Q.13 COP and efficiency formula?
Answer- Well there is relation between COP and efficiency that is 1 + COP(R) = COP(HP) = 1/ηHE
In refrigeration we have two common machine one of them is refrigerator and another one is heat pump, both work in the same cycle.
Q.14 What is EER? Which is related to COP?
Answer- Energy Efficiency Ratio(EER) is defined as the ratio of energy performance of heating and cooling equipment.
Q.15 What is the difference between COP and Carnot efficiency?
Answer- COP is the ratio of desire effect to work input, Carnot efficiency is the maximum efficiency we can get from any cycle.
Q.16 Why is it called COP and not efficiency?
Answer- One basic reason behind it that is the cycle is in reversed direction, therefore even COP can be greater than 1.
Q.17 Is COP the same as efficiency?
Answer- No, both are different, COP full form is coefficient of performance, in case of work absorbing device we used term COP like refrigerator but in case of work producing device we used efficiency term like heat engine.
COP & Efficiency MCQ’s with Solution-
1. In a refrigeration system, the COP is defined as:
A) the ratio of work output to heat input
B) the ratio of heat removed from the cooled space to energy consumed by the system
C) the ratio of heat input to work output
D) the ratio of energy consumed by the system to heat removed from the cooled space
Solution: B) the COP in a refrigeration system is defined as the ratio of heat removed from the cooled space to energy consumed by the system.
2. In a heat engine, the thermal efficiency is defined as:
A) the ratio of work output to heat input
B) the ratio of heat removed from the cooled space to energy consumed by the system
C) the ratio of heat input to work output
D) the ratio of energy consumed by the system to heat removed from the cooled space
Solution: A) in a heat engine, the thermal efficiency is defined as the ratio of work output to heat input.
3. The COP of a refrigeration system can be increased by:
A) increasing the energy input to the system
B) decreasing the energy input to the system
C) increasing the heat removed from the cooled space
D) decreasing the heat removed from the cooled space
Solution: B) the COP of a refrigeration system can be increased by decreasing the energy input to the system.
4. The thermal efficiency of a heat engine can be increased by:
A) increasing the heat input to the system
B) decreasing the heat input to the system
C) increasing the work output of the system
D) decreasing the work output of the system
Solution: C) the thermal efficiency of a heat engine can be increased by increasing the work output of the system.
5. The COP of a refrigeration system is always:
A) greater than 1
B) less than 1
C) equal to 1
D) dependent on the type of refrigerant used
Solution: A) the COP of a refrigeration system is always greater than 1, as it represents the proportion of heat moved by the system compared to the energy input to the system.