Chemical Engineering - Heat Transfer - Discussion
Discussion Forum : Heat Transfer - Section 1 (Q.No. 20)
20.
The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are
Discussion:
12 comments Page 1 of 2.
Harika said:
3 years ago
Nice explanation. Thankyou.
Nakachew Munwyelet said:
6 years ago
(COP)R = Qc/(Qh-Qc)=(Qc/Qh)/(1-Qc/Qh)
Thermal efficiency = (Qh-Qc)/Qh = 1-Qc/Qh.
Qc/Qh = 1 - Thermal efficiency.
(COP)R = (1-Thermal efficiency)/Thermal efficiency,
(COP)hp = Qh/(Qh-Qc)=1/(1-Qc/Qh) = 1/Thermal efficiency,
(COP)R = (1-Thermal efficiency)/Thermal efficiency,
= (1/Thermal efficiency)-1 = (COP)hp-1.
(COP)R = (COP)hp-1.
(COP)hp = (COP)R+1.
Thermal efficiency = (Qh-Qc)/Qh = 1-Qc/Qh.
Qc/Qh = 1 - Thermal efficiency.
(COP)R = (1-Thermal efficiency)/Thermal efficiency,
(COP)hp = Qh/(Qh-Qc)=1/(1-Qc/Qh) = 1/Thermal efficiency,
(COP)R = (1-Thermal efficiency)/Thermal efficiency,
= (1/Thermal efficiency)-1 = (COP)hp-1.
(COP)R = (COP)hp-1.
(COP)hp = (COP)R+1.
Prakash Dhanaraj said:
7 years ago
How comes (cop)hp = (cop)r+1.?
Please explain.
Please explain.
Aksha vetal said:
9 years ago
Thermal efficiency is given by:
= (Heat transferred from higher value to lower value)/Higher value.
= (Qh - Ql)/Qh.
Thermal efficiency = 0.4 = 1- (Ql/Qh).
So,
Ql/Qh = 0.6,
Qh/Ql = 1/0.6,
(cop)R = (1 - thermal efficiency)/thermal efficiency,
(COP)R = (1- 0.4)/0.4,
(COP)R = 0.6/0.4,
= 1.5.
(COP)HP = (COP)R + 1,
= 1.5 + 1,
= 2.5.
= (Heat transferred from higher value to lower value)/Higher value.
= (Qh - Ql)/Qh.
Thermal efficiency = 0.4 = 1- (Ql/Qh).
So,
Ql/Qh = 0.6,
Qh/Ql = 1/0.6,
(cop)R = (1 - thermal efficiency)/thermal efficiency,
(COP)R = (1- 0.4)/0.4,
(COP)R = 0.6/0.4,
= 1.5.
(COP)HP = (COP)R + 1,
= 1.5 + 1,
= 2.5.
(11)
Sanket said:
1 decade ago
(cop)R = (1-thermal efficiency)/thermal efficiency.
(cop)Hp = 1+(cop)R.
(cop)Hp = 1+(cop)R.
V G Sunjay Jeffrish said:
1 decade ago
Efficiency can also be 1-tc / th.
Where tc cold body.
Th hot body.
Where tc cold body.
Th hot body.
Ankita said:
1 decade ago
@ Shubham.
Thermal efficiency is given by:
= (Heat transferred from higher value to lower value)/Higher value.
= (Qh-Ql)/Qh.
Hence the formula.
Thermal efficiency is given by:
= (Heat transferred from higher value to lower value)/Higher value.
= (Qh-Ql)/Qh.
Hence the formula.
Shubham said:
1 decade ago
Thermal efficiency = 0.4 = 1-(Ql/Qh).
This term is not understand. Please again explain.
This term is not understand. Please again explain.
Shan Rana said:
1 decade ago
Ql = Lower heat energy.
Qh = Higher heat energy.
Qh = Higher heat energy.
Chandana said:
1 decade ago
What is Ql and Qh?
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