This document summarizes key concepts in refrigeration cycles. It defines refrigeration as reducing the temperature below the surroundings and notes that refrigerants, like NH3, are used as working fluids. It explains that the refrigerating effect is the energy removed from the cold chamber and that the coefficient of performance is the ratio of heat removed to work input. The document also discusses refrigerator capacity as the amount of heat transferred per unit time from the cold chamber. It provides an overview of the vapor compression refrigeration cycle and notes modifications to improve efficiency, such as replacing the expansion engine with a throttling valve.

1. D.M.Gamage
Basic concept & Theory

2. Refrigeration cycle
 Reducing of the temperature of an object below
the surrounding temperature is called as
Refrigeration
Refrigerant
In this refrigeration working fluid known as refrigerant.
Ex- NH3

3. Refrigerating effect
 In the refrigerator the important quantity is the
energy remove from the cold chamber which is
known as refrigerating effect.
CO-efficient of Performance
• Co-efficient of performance is defined as the ratio
between the heat remove from the cold chamber and
the work Input in the system.
• COP=
𝑅𝐸 𝑒𝑓𝑓𝑒𝐶𝑡
𝑤 𝑖 𝑛

4. Refrigerator Capacity
 The most important quantity in application of a
refrigerator is the amount of heat which must be
transferred per unit time from the cold chamber
and is known as refrigerator capacity.
Mass flow rate of Refrigeration
Refrigeration capacity divide by Refrigeration
effect per unit mass

5. Vapor compression Refrigeration cycle
 A liquefiable vapor is used as the refrigerant.

6. 1-2 isentropic Compression of wet vapor
2-3 Heat rejection at constant Temperature
3-4 isentropic expansion of saturated liquid
4-1 Heat absorb at constant temperature

7. The best COP will be given by the Carnot
cycle.

8. Modification of the Carnot cycle of
vapor compression refrigeration cycle
Replacement of
expansion
engine with
throttling value
Improving
the
condition of
compressor
inlet
Under cooling
of condenser
outlet

9. Replacement of expansion engine with
throttling value
Throttling process is constant enthalpy process. But highly irreversible.

10. Improving the condition of compressor inlet

11. Under cooling of condenser outlet

12. Equation

13. The pressure –enthalpy diagram

14. P-h diagram for Carnot cycle
P-h diagram for Replacement of expansion engine with throttling value

15. Improving the condition of compressor inlet
Under cooling of condenser outlet

16. Question

20. Thank you