4.4 Coefficient of Performance Report.pptx

Coefficient of Performance Report

1. 4.4 Coefficient of Performance Prepared by : 3cl Quianzo , Ghavy Angelo A.

2. What is Coefficient of Performance?

3. The Coefficient of Performance (COP) is a performance rating that tells us how effective a heat pump or air conditioner is in transferring heat versus the amount of electrical power it consumes.

4. Why COP is expressed as a number?

5. By convention COP is expressed as a dimensionless number. The coefficient of performance (COP) is typically expressed as a numerical value because it represents a ratio of two quantities : the desired output (e.g., heat transferred) to the required input (e.g., energy input).

6. Does it have a formula?

7. Mathematically, the coefficient of performance (COP) is expressed as: For a refrigeration system, the desired output is the amount of heat removed from the cold space, and the required input is the energy input to the system.

8. For example, if the COP of a heat pump is 3, it means that for every unit of energy input into the system, it can transfer 3 units of heat to the desired space. This ratio is a dimensionless quantity and is simply a measure of efficiency.

9. There are two COPS: 1. COP of cooling [refrigeration/air conditioning] COP of cooling = Qc/W [ Qc is cold space heat and W is work by compressor] 2 . COP of heating [heat pump] COP of heating = [W + Qc]/W by compressor

10. 1. COP of cooling [refrigeration/air conditioning] In this image, refrigerators extract heat from the interior and expel it to the external environment, maintaining a temperature below room temperature.

11. 2. COP of heating [heat pump] In this image, heat pumps, on the other hand, transfer heat from a colder area to a warmer area in heating mode and remove heat from space in cooling mode.

12. 4.5 Refrigeration system arrangement on board

13. Why are refrigeration systems necessary on ships?

14. The main purpose of a ship’s refrigeration plant is to avoid any damage to the cargo or perishable material so that it is transported in good and healthy condition. Refrigeration prevents the growth of micro-organisms, oxidation, fermentation drying out of cargo etc.

15. What are the main components of refrigeration plants?

16. Main Components: 1. Compressor : A reciprocating single or two-stage compressor is commonly used for compressing and supplying the refrigerant to the system.

17. Main Components: 2. Condenser : Shell and tube type condenser is used to cool down the refrigerant in the system. 3. Receiver : The cooled refrigerant is supplied to the receiver, which is also used to drain out the refrigerant from the system for maintenance purpose.

18. Main Components: 4. Drier : The drier connected in the system consists of silica gel to remove any moisture from the refrigerant 5. Solenoids : Different solenoid valves are used to control the flow of refrigerant into the hold or room. Master solenoid is provided in the main line and other solenoid is present in all individual cargo hold or rooms.

19. Main Components: 6. Expansion valve : An Expansion valve regulates the refrigerants to maintain the correct hold or room temperature. 7. Evaporator unit : The evaporator unit act as a heat exchanger to cool down the hold or room area by transferring heat to the refrigerant.

20. Main Components: 8. Control unit : The control unit consist of different safety and operating circuits for safe operation of the refer plant.

21. How refrigeration system works onboard?

22. What are the Safety Devices on the Refrigeration System of a Ship?

23. The main safeties adopted for refrigeration plants are: 1. Low Pressure or LP cut off:

24. The main safeties adopted for refrigeration plants are: 2. High pressure or HP cut out: Unknown. (2016, July 26). Construction and Working of Ships Refrigeration plant. https://marineexam.blogspot.com/2016/07/construction-and-working-of-ships.html

25. The main safeties adopted for refrigeration plants are: 3. Oil differential cut out: This safety is again for compressor as it is the only machinery in the circuit having rotational parts which requires continuous lubrication. In the event of low supply or no supply of lube oil to the bearing, the differential pressure will increase and activates a trip signal to safeguard the bearing and crankshaft.

26. The main safeties adopted for refrigeration plants are: 4. Relief valves: Relief valves & Pressure reducing valves - Ship service systems . (n.d.). http://generalcargoship.com/relief-valves.html

27. The main safeties adopted for refrigeration plants are: 5. Solenoid valves: Solenoid valves for refrigeration systems . (n.d.). Danfoss. https://www.danfoss.com/en/service-and-support/case-stories/dcs/solenoid-valves-for-refrigeration-systems/

28. The main safeties adopted for refrigeration plants are: 6. Oil heater: Watch, O. O. T. (2014, March 15). Thermal oil heater explosion onboard oil tanker – investigation report. Officer of the Watch. https://officerofthewatch.com/2013/12/16/thermal-oil-heater-explosion-onboard-oil-tanker-investigation-report/

29. How to Charge Refrigeration Plant on Ships?

30. • Short Cycling of Compressor • Too low suction pressure • Difficult to maintain temperature of rooms and holds • Reduction in the efficiency of the plant Note: When the above mentioned problems occur, it indicates that the plant has to be charged with the refrigerant.

31. There are two methods for charging reefer plants: Liquid charging Gas charging Note: Nowadays gas charging is preferred over liquid charging because it is safer and simpler.

32. Gas Charging of Refrigeration Plant : For gas charging, a special T-piece valve block with a mounted pressure gauge is provided to combine three connectors inter-connecting: -Vacuum pump -Charging Cylinder -Charging Point

33. -Vacuum pump -Charging Cylinder -Charging Point Unknown. (2016, July 26). Construction and Working of Ships Refrigeration plant. https://marineexam.blogspot.com/2016/07/construction-and-working-of-ships.html

34. The following steps are to be taken for charging gas into the reefer plant: Connect gas bottle or charging cylinder, vacuum pump and charging point in the reefer system to the valve block. The discharge of the vacuum pump is to be connected in the empty recovery bottle

35. The following steps are to be taken for charging gas into the reefer plant: 3. First open the valve between vacuum pump and charging bottle located in the valve block without opening the main valve of the charging cylinder. This will remove all the air inside the pipe. Once vacuum is reached, close the valve of charge cylinder in the valve block

36. The following steps are to be taken for charging gas into the reefer plant: 4. Now open the valve of the charging point pipe in the valve block and run the vacuum pump until the vacuum is reached. This will remove the trapped air from this pipe. Then shut the valve in the valve block 5. Now keep the system idle for 5 minutes to check there is no pressure drop. This will ensure there are no leakages in the system

37. The following steps are to be taken for charging gas into the reefer plant: 6. Now open charging bottle pipe valve and the charging point pipe valve located in the valve block. This will set the line for charging. Ensure that the vacuum pump valve is shut 7. Now open the main valves in the charging cylinder and charging point of the reefer system

38. The following steps are to be taken for charging gas into the reefer plant: 8. Do not overfill the system. Make sure the receiver has 5 % space for expansion. Ensure that no refrigerant is leaked out in the environment as these effects the ozone layer in the atmosphere.

39. Cite Sources: Mukherjee, N. (2023, November 14). The coefficient of performance [COP]: Refrigeration vs. Heat pump. https://www.linkedin.com/pulse/what-coefficient-performance-cop-nikhilesh-mukherjee-egrmf/ Unknown. (2016, July 26). Construction and Working of Ships Refrigeration plant. https://marineexam.blogspot.com/2016/07/construction-and-working-of-ships.html Heinen & Hopman. (2024, March 15). Marine Refrigeration System - Heinen & Hopman. https://www.heinenhopman.com/marine-refrigeration-system/ Eriscson , M. (2019, April 13). Marine refrigeration system working. Marinersgalaxy . https://marinersgalaxy.com/marine-refrigeration-system-requirements/ Watch, O. O. T. (2014, March 15). Thermal oil heater explosion onboard oil tanker – investigation report. Officer of the Watch. https://officerofthewatch.com/2013/12/16/thermal-oil-heater-explosion-onboard-oil-tanker-investigation-report/ Solenoid valves for refrigeration systems. (n.d.). Danfoss. https://www.danfoss.com/en/service-and-support/case-stories/dcs/solenoid-valves-for-refrigeration-systems/ Relief valves & Pressure reducing valves - Ship service systems. (n.d.). http://generalcargoship.com/relief-valves.html

40. Thank you for listening!