5.88 The steady-state data listed below are claimed for a power cycle operating

Question

5.88 The steady-state data listed below are claimed for a power cycle operating between hot and cold reservoirs at 1200 K and 400 K, respectively. For each case, evaluate the net power developed by the cycle, in kW, and the thermal efficiency. Also in each case apply Eq. 5.13 on a time-rate basis to determine whether the cycle operates reversibly operates irreversibly, or is impossible. (a) QH = 600 kW. Qc = 400 kW (b) QH-600 kW, QC = 0 kw (c) QH = 600 kW, Qc = 200 kW toto n thermodynamic cycle operating between lun

Explanation / Answer

Th=1200k, Tc= 400

efficiency n = (Th-Tc)/Tc

n = (1200-400)/1200 = 0.667

(a) QH =600 kW, QC = 400 kW

n = (QH-QC)/QH = (600-400)/600

n = 0.33

0.33<0.67

So it is irreversible process

(b) QH =600 kW, QC =0

n =(600-0)/600 =1

efficiency is never be equal to one.

So it is impossible process.

(c)

QH =600 kW, QC =200 kW

n =(600-200)/400

n = 0.67(it is equal to n value from temperature)

SO it is reversible process

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