Saturday, May 4, 2013

Rules of Thumb in Refrigeration Engineering


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

and Techniques.


Part 1

During my professional duties as Lecturer in R&AC in a Humberside college of HE&FE we

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.