Applied Thermodynamics 2nd. Edition by R.K. RAJPUT | 9788131805831 | Holooly

Applied Thermodynamics

394 SOLVED PROBLEMS

Question: 5.7

Steam initially dry and saturated is expanded in a nozzle from 15 bar at 300°C to 1.0 bar. If the frictional loss in the nozzle is 12% of the total heat drop calculate the mass of steam discharged when exit diameter of the nozzle is 15 mm. ...

Verified Answer:

Refer Fig. 10. Pressure, ...

Question: 6.18

In a single stage steam turbine saturated steam at 10 bar abs. is supplied through a convergent-divergent steam nozzle. The nozzle angle is 20° and the mean blade speed is 400 m/s. The steam pressure leaving the nozzle is 1 bar abs. Find : (i) The best blade angles if blades are equiangular. (ii) ...

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Supply steam pressure (to nozzles) = 10 bar abs. N...

Question: 5.1

(a) Mention the types of nozzles you know. Where are these used ? (b) From first principles, prove that maximum discharge per unit area in a steam nozzle at the throat is given by the expression ...

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(a) Types of nozzles : 1. Convergent nozzle. It is...

Question: 3.15

A double-acting single-cylinder steam engine runs at 250 r.p.m. and develops 30 kW. The pressure limits of operation are 10 bar and 1 bar. Cut-off is 40% of the stroke. The L/D ratio is 1.25 and the diagram factor is 0.75. Assume dry saturated steam at inlet, hyperbolic expansion and negligible ...

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Speed of the steam engine, ...

Question: 11.5

Calculate the thermal efficiency and work ratio of the plant is example 25.4, assuming that cp for the combustion process is 1.11 kJ/kg K. ...

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Heat supplied=

c_{p} (T_{3} – T_...

Question: 12.16

(i) What are the advantages of using an expansion valve instead of an expander in a vapour compression refrigeration cycle ? (ii) Give a comparison between centrifugal and reciprocating compressors. (iii) An ice-making machine operates on ideal vapour compression refrigeration ...

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(i) If an expansion cylinder is used in a vapour c...

Question: 12.27

The evaporator and condenser temperatures of 20 tonnes capacity freezer are – 28°C and 23°C respectively. The refrigerant – 22 is sub-cooled by 3°C before it enters the expansion valve and is superheated to 8°C before leaving the evaporator. The compression is isentropic. A sixcylinder ...

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Refer to Fig. 37. Following the procedure as given...

Question: 12.26

A refrigeration system of 10.5 tonnes capacity at an evaporator temperature of – 12°C and a condenser temperature of 27°C is needed in a food storage locker. The refrigerant ammonia is sub-cooled by 6°C before entering the expansion valve. The vapour is 0.95 dry as it leaves the evaporator ...

Verified Answer:

Refer to Fig. 36. Using p-h chart for ammonia, • L...

Question: 12.25

A food storage locker requires a refrigeration system of 2400 kJ/min. capacity at an evaporator temperature of 263 K and a condenser temperature of 303 K. The refrigerant used is freon-12 and is subcooled by 6°C before entering the expansion valve and vapour is superheated by 7°C ...

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The cycle of refrigeration is represented on T-s d...

Question: 12.24

A vapour compression heat pump is driven by a power cycle having a thermal efficiency of 25%. For the heat pump, refrigerant-12 is compressed from saturated vapour at 2.0 bar to the condenser pressure of 12 bar. The isentropic efficiency of the compressor is 80%. Saturated liquid ...

Verified Answer:

Heat rejected by the cycle =

\frac{500}{0...

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