Thermodynamics - 6-4 Refrigerators and Heat Pumps - another example

[@husnakn5004]

Where did the 30 degrees of the house come from

[@Giannis_Papa]

How do we know that the refrigerant at 50 C is superheated vapor and not saturated liquid/vapor or mixture ?

[@bountyhunter4985]

really helpful. thanks

[@mumtazahumairah1516]

Is the value of h1 taken from superheated refrigerant table?

[@sunmichoi6888]

Thank you!!!

[@erendastan6158]

from which table did we take the enthalpy value of the one which at 45 C? There is no 45C at the table superheated refrigeant-134a

[@engineeringdeciphered]

Correct there is no 45 on the superheated because it is not superheated. For a pressure of 1.2, the tsat is 46.29, so it is subcooled. If we had a subcooled (or compressed) liquid table we would look there. But since we done have a table for that, we’ll just estimate it as the hf at the given temp. So go to table A11 and look up 45C. You’ll have to interpolate (or just take the mean) of the hf at 44 and the hf at 46.

[@yusrahamer5979]

why did we use the enthlapy h and not the eternal energy u ?

[@lakshyaadatrow]

ya why??

[@libidwana3403]

@@lakshyaadatrow steady flow device

[@xdsilver3249]

where could i find part d solution? thx

[@maritessegovia758]

can I buy the complete notes that you wrote? does it include chapter 8 to chapter 18?

[@engineeringdeciphered]

No, it’s only chapters 1-7. Look at the free fill in the blank notes first to see if you want to buy the completed notes.

[@Mrandyriadh]

How come you don't teach the rest of the chapters?@@engineeringdeciphered

[@DiyaPatel-v9r]

for Q(L) my math is coming Negetive. What does negetive mean for QL

[@haifa3061]

its heat out so losing heat

[@kylecatman7738]

R134a at 50C and 1200 kPa is 426.84 kJ/kg and hf (at saturation liquid) 45C is 264.11 kJ/kg.

[@engineeringdeciphered]

again, double checking my tables, but I've got that R134a at 50C and 1200kPa is 278.28 kj/kg. And hf at 45 would be the average of 117.34 and 114.30.

[@engineeringdeciphered]

I’m using Cengel and Boles property tables. You can look in table A13 and A11 www.dropbox.com/scl/fi/l5ir7947mx69qm3i1bq1t/Property-Tables-Appendices-1-and-2.pdf?rlkey=ombvp8i0xpxmllg31fdts1y8p&dl=0

[@LusandaThabethe]

@@engineeringdeciphered Since in the video you claimed its still superheated after passing through the condenser, why don't we take hg from A11.I see that you used hf.

[@yakamoz5673]

R you drunk?