COP Of Air Refrigerator Working On Reversed Carnot Cycle with PV and Ts Diagram

reversed carnot cycle pv diagram ts diagram

Introduction to the Air Refrigerator working on reversed Carnot cycle

In these type of refrigerator, a reversed Carnot cycle is considered. For a heat engine, the highest possible efficiency is achieved by the Carnot cycle. Similarly in refrigeration cycle highest possible coefficient of performance is obtained when the system is working on reversed Carnot cycle. However, it is not possible to make an engine operating on the Carnot cycle, or it is not possible to make a refrigerating system working on reversed Carnot cycle. This hypothetical heat cycle is used as a standard of comparison.

- Air Refrigerator working on Bell-Coleman cycle with PV and TS diagram (reversed Brayton or Joule Cycle)
- Mechanism and working of a vapour compression refrigeration system - with PV And TS diagram

P-V and T-S Diagrams of reversed Carnot cycle - Process involved

Fig (1) and fig(2) shows the p-v and T-s diagram of a refrigeration system working on reversed Carnot cycle. The process involved in reversed Carnot cycles are as follows

1-2. isentropic compression process
During this stage, air is compressed isentropically. Pressure and temperature increases, the specific volume of decreases. During isentropic compression, there is no heat exchanging (absorb and rejection) takes place by air.

2-3 Isothermal compression
After isentropic compression air again compress isothermally (constant temperature). The pressure increases while specific volume decreases. The heat rejected during isothermal compression per kg of air
q2-3 =T3(S2-S3) = T2(S2-S3)

3-4. Isentropic expansion process
The air expands isentropically as shown in above figure. Pressure decreases from P3 to P4, specific volume increases from v3 to v4. The temperature also decreases. There is no heat transfer by air during this process.

4-1. Isothermal expansion process
The air expands at a constant temperature. The pressure of air decreases while the specific volume of air increases. During this process, the heat absorbed by air per kg of air
Q4-1 = T4(S1-S4) = T4(S2-S3) = T1(S2-S3)

Coefficient of performance of Refrigerator working on reversed Carnot cycle

Read: Coefficient of performance and relative coefficient of performance of refrigeration cycle

Net work done during reversed Carnot cycle per kg of air is = Heat rejected - heat absorbed.
= q2-3 - q4-1
T2(S2-S3) - T1(S2-S3)
Coefficient of performance (COP)R = Heat absorbed / Work done = q4-1/(q2-3 - q4-1)
(T_1 (S_2-S_3))/((T_2-T_1)(S_2-S_3))=  T_1/(T_2-T_1 ) cop equation reversed carnot cycle

What Is Refrigeration Load? Cooling Load, Heating Load

chair pillow radiation curtain window

Cooling load

Cooling load is defined as the average rate at which the heat is removing from the cold space by refrigeration equipment. Similar to the unit of refrigeration it is also expressed in Ton of refrigeration (TR).  The building design, internal equipment, occupants, and outdoor weather conditions may affect the cooling load. Following are the common sources of heat that contribute to the cooling load of refrigeration equipment.

  • Heat emitted by the people occupied in refrigerated space/ objects whose temperature is to be lowered.
  • Heat generating equipment’s in refrigerated space Eg: lamps, motors, etc.
  • Solar radiation entered the cold space through the transparent material.
  • Warm air/ Heat entered the refrigerated space through open doors and windows or any cracks in wall/ poor insulated wall.

The importance of each source may vary according to the application so that the total cooling load will vary considerably with the different application.

Heating load

This is applicable when space is needed to keep warm. Heating load is defined as the average rate of heat to be supplied to the air-conditioned space to keep it warm.

What is Unit of refrigeration or Rating for Refrigeration - Derivation

refrigeration shop

Unit of refrigeration

Rating for Refrigeration indicates the rate of removal heat. The unit of refrigeration is expressed in terms of ton of refrigeration (TR). One ton of refrigeration is defined as the amount of refrigeration effect (heat transfer rate) produced during uniform melting of one ton (100kg) of ice at 0°C to the water at the 0°C in 24 hours.

Mechanism And Working Of A Vapour Compression Refrigeration System - With PV And TS Diagram

vapour compression refrigeration

The above figure shows simple vapour compression refrigeration system. In this type of refrigerator, refrigerant undergoes phase changes. It consists of following components.

Air Refrigerator Working On Bell-Coleman Cycle with PV and TS Diagram (Reversed Brayton or Joule Cycle)

bell coleman diagram

Fig shows a schematic diagram of Bell-Coleman refrigerator (reverse Brayton or joule cycle). It consists of a compressor, cooler, Expander, and refrigerator. In this process, heat absorption and rejection follows at the constant pressure; the compression and expansion of process are isentropic.

What Is Clamping Devices? Requirements of Clamping Devices


Clamping device are used to minimize the distortion during the machining process. Once the workpiece is located, it is necessary to hold it against the machining force. The mechanism used for this is known clamps. They are work holding devices usually positioned above the supporting surfaces. Fibre pads are riveted to the face of clamps where the metallic clamp get contact with the workpiece to avoid damage by metallic contact.