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In an experimental set – up, air flows between two stations P and Q adiabatically. The direction of flow depends on the pressure and temperature conditions maintained at P and Q. The conditions at station P are 150 kPa and 350 K. The temperature at station Q is 300 K.
The following are the properties and relations pertaining to air:
Specific heat at constant pressure,Cp =1.005 kJ.kgK;
Specific heat at constant volume,Cv =0.718 kJ/kgK;
Characteristic gas constant,R=0.287 kJ.kgK.
Enthalpy, h=Cp T
Internal energy, u=CvT .
[1] If the pressure at station Q is 50 kPa, the change in entropy (SQ -SP ) in kJ/kgK is
[2 marks]
(A) -0.155
(B) 0
(C) 0.160
(D) 0.355[2] If the air has to flow from station P to station Q, the maximum possible value of pressure in kPa at station Q is close to [2 marks]
(A) 50
(B) 87
(C) 128
(D) 150asked in Mechanical Engineering, 2011
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14.
One unit of product P1 requires 3 kg of resource R1 and 1 kg of resource R2 . One unit of product P2 requires 2 kg of resource R1 and 2 kg of resource R2. The profits per unit by selling product P1 and P2, are Rs. 2000 and Rs. 3000 respectively. The manufacturer has 90 kg of resource R1 and 100 kg of resource R2 .
[1] The manufacturer can make a maximum profit of Rs. [2 marks]
(A) 60000
(B) 135000
(C) 150000
(D) 200000[2] The unit worth resource R2 , i.e. dual price of resource R2 in Rs. per kg is [2 marks]
(A) 0
(B) 1350
(C) 1500
(D) 2000last reply by CpjJwWHV • 8 years ago • asked in Mechanical Engineering, 2011
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