The rules of thumb article below is a part in series of lecturers of Prithvi Datta (UK) ] he used at
Colleges of HE & FE in United Kingdom with practical experimentation for promoting innovation and
modification in R&HVAC Engineering.Thousands of Trainers of Trainees and students of courses from
Apprentice Mechanic to Ph.D. had appreciated the series to master skills for Experimental Studies
were using R12,22 or 502 for following use of Rule of Thumbs. I tried to use R410A for the
following example using limited data available to me at that moment.Selected R410 for this
application with COP of 8.33 is good example.
why some refrigerant cannot be used without waste of energy and operational and capital
losses.Phase & State of Refrigerant at important specific points within as simple
Refrigeration Cycle working in UK with R410A working at ambient temp. 25 deg for
refrigeration duty of - 20 deg. C (ignoring pressure drop caused within the pipework).
Refrigeration Cycle should be studied at 12 specific point in the cycle
with R410A working at ambient temp. 25 deg for refrigeration duty of - 20 deg. C Refrigeration Cycle should be studied at 12 specific point in the cycle
Ability to forecast State and Phase of Refrigerant at these 12 points and mastering P-h
Chart using these 12 points can allow true professionals to raise energy efficiency of
Refrigeration Systems and gain best of trouble shooting skills.
High Side of Cycle
Point Position State. State. Phase of Refrigerant
1. Inlet of Compressor 3 -18 Superheated Gas
2. Outlet of Compressor 25 80 Superheated Gas
3. Inlet to Condenser 25 70 Superheated Gas
4. 1/8 of Condenser 25 40 Saturated Vapour
5. ½ of Condenser 25 40 45% Vapour +55% Liquid
6. 7/8 of Condenser 25 40 100% Saturated Liquid
7. Outlet of Condenser 25 33 Subcooled Liquid
8. Inlet of Metering device 25 32 Subcooled Liquid
Low Side of Cycle
9. Outlet of MD 3 -28 Liquid with Flash Gas
10. inlet of Evaporator 3 -28 Liquid with Flash Gas
11. ½ of Evaporator 3 -28 45% Liquid + 55% Vapour
12. Outlet of Evaporator 3 -22 Superheated Gas
Please visit the site for the next post for the Part-2 of the Rules of Thumbs.