An insulated rigid tank is divided into two equal parts by a partition. Initially, one part contains 4 kg of an ideal gas at 800 kPa and 50°C, while the other part is evacuated. The partition is now removed and the gas expands into the entire tank. Determine the final temperature and pressure in the tank.

1.(b) Show processes of saturated vapour compression refrigeration cycle on t-s and p-h diagram and mark graphically on t-s diagram refrigerating effect, heat rejection by condenser and compressor work.

1.(c) What is the shape factor in case of radiative heat exchange? Discuss the four basic shape factor laws.

1.(d) Draw valve timing diagrams of 4-stroke high speed and low speed SI internal combustion engine.

1.(e) Define steam, quality and derive expression for specific volume of steam in terms of steam quality. v vf xvfg.

2.(a) The efficiencies of the compressor and turbine of a gas turbine are 70% and 71 respectively. The heat added in the combustion chamber per kg of air is 476·35 kJ/kg. Find a suitable pressure ratio such that the work ratio is 0·054. Also find the corresponding temperature ratio. The inlet total temperature of air is 300 K.

2.(b) A flue gas stream is to be monitored for its temperature using a thermocouple. The thermocouple design needs to be evaluated in terms of its time response to accurately predict the measured temperature. The thermocouple junction can be approximated as a sphere of diameter 0·6 mm, density of the bead material 8500 kg/m^3 thermal conductivity is 30 specific heat is 0·3 kJ/kg-K. The convective heat transfer coefficient between the junction and flue gas is 300 W/m2-K. Determine the time required to read 90% of the initial temperature difference. Neglect radiation effect and change in thermophysical properties with temperature.

2.(c) Classify different types of boilers and discuss factors important for the boiler
selection.

3.(a) In an open heart surgery, under hypothermic conditions, the patient's blood is cooled before surgery and rewarmed afterwards. It is proposed that a concentric tube counterflow heat exchanger of length 0·5 m is to be used for this purpose, with a thin walled inner tube having diameter of 55 mm. If water at 60°C and 0·1 kg/s is used to heat the blood entering the heat exchanger at 18°C at a flow rate of 0·01 what is the temperature of the blood leaving the heat exchanger? One may assume, overall heat transfer coefficient 500 specific heat of blood and water are respectively CPblood 3·5 Cpwater 4·187 kJ/kg-K.

3.(b) A single cylinder 4 stroke Sf engine is producing 100 KW power at an overall efficiency of 20%. Engine uses a fuel-air ratio of 0·07: Determine how many m^3/hr of air is used if air density is 1·2 kg/m3 The fuel vapour density is 4 times that of air. How many m^3/hr of mixture is required? Calorific value of fuel is 42000 kJ/kg.

3.(c) The pressure in an automobile tyre depends on the temperature of the air in the tyre. When the air temperature is 25°C, the pressure gauge reads 210 kPa. If the volume of the tyre is 0·025 detemline the pressure rise in the tyre when the air temperature in the tyre rises to 50cC. Also, determine the amount of air that must be bled off to restore pressure to its original value at this temperature. Assume the atmospheric pressure is 100 kPa and gas constant of air, R 0·287 kPa m^3/kg-K.

4.(a) A six cylinder 4-stroke diesel engine has a bore of 60 mm and a crank radius of 32 mm. The compression ratio is 9 I and engine volumetric efficiency is 90%.

Determine: Stroke length

(ii) Mean piston speed at 1000 rpm

(iii) Swept volume per cylinder
Clearance volume per cylinder Cubic capacity of the engine

(vi) Actual volume of air aspirated per stroke in each cylinder


4.(b) The rotor of an axial flow fan has a mean diameter of 30 cm. It runs at 1470 rpm. Its velocity triangles at entry and exit are described by the following data: Peripheral velocity components of the absolute velocities at entry and exit are:

Cy1 1/3 Cy2 2/3 u where, C fluid velocity, u peripheral speed Draw the inlet and exit velocity triangles for the rotor and prove that the work is given by Wc 1/3 u^2

(ii) Calculate the pressure rise, take a constant density of air, p 1·25 kg/m^3.

4.(c) Explain clearly what is "thermally developed zone" in case laminar flow through a tube both for constant wall temperature case

(ii) constant heat flux case.

5.(a) What is the difference between 'normal' and 'oblique' shock? State the significance of each.

5.(b) Explain harmful effects of R-12 and R-22 refrigerant. Write their chemical fom1Ula and NBP temperature. Also suggest new ecofriendly substitutes of these two with chemical composition.

5.(c) Discuss experimental determination of calorific value of solid fuel with a neat diagram.

5.(d) The air-fuel ratio of an SI engine varies from no-load to full load condition. Write air-fuel ratio requirement for an engine under following conditions with reason:
Idling condition
Cruising condition

(iii) High load condition
Cold-start condition

5.(e) A sample of fuel was found to have the following percentage analysis by weight: C 80; H2 16; and ash etc. 4. Determine the minimum weight and volume of air required to bum 1 kg of this fuel. Density of O2 is 1·429 kg/m^3.

6.(a)

<img src='./qimages/15694-6a.jpg'>

A single stage, single acting vapour compression refrigeration system uses R-134a. Condenser and evaporator temperatures are 35°C and -lOoC and refrigerant is undercooled by 5°C. Clearance volume per swept volume is 0·03 and swept volume is 269-4 cm3. Compressor speed and efficiency are 2800 rpm and 80% respectively. Expansion index is 1·12. Determine Compressor exit temperature Enthalpy of refrigerant at compressor exit Enthalpy at the exit of the subcooler Volumetric efficiency of compressor Refrigerant mass flow rate. Specific heat of vapour and liquid at condenser pressure are 1·1 kJ/kg-K and 1-458 kJ/kg-K respectively. Assume suction vapour dry saturated and isentropic compression:

6.(b) Explain about back pressure turbine

(II) by-product power cycle

(III) co-generation plant

(IV) tri-generation plant.

(ii) Define overall efficiency, boiler efficiency, cycle efficiency, mechanical efficiency and generator efficiency of a Rankine cycle based power plant and also prove that:

noverall nboiler x ncycle x n mechanical x ngenerator

6.(c) A supersonic wind tunnel settling chamber expands air through a nozzle from a pressure of lObar to 4 bar in the test section. Calculate the stagnation temperature to be maintained in the settling chamber to obtain a velocity of 500 rn/s in the test section. Take Cp, air ]·025 kJ/kg-K and Cv, air O· 735 kJ/kg-K.

7.(a) The mean diameter of the blades of an impulse turbine with a single row wheel is 105 cm and the speed is 3000 rpm. The nozzle angle is the ratio of blade speed to steam speed is 0-42 and the ratio of the relative velocity at outlet from the blades to that at inlet is 0·84. The outlet angle of the blade is to be made 3° less than the inlet angle. The steam flow is 8 kg per sec, Draw the velocity diagram for the blades and estimate the resultant thrust on the blades

(ii) tangential thrust on the blades

(iii) axial-thrust on the blades

(iv) power developed in blades and blade efficiency.



7.(b)

<img src='./qimages/15694-7b.jpg'>

A small disc-shaped earth satellite, I m in diameter circles the earth (radius 6250 km) at a distance of 300 km from the surface. The flat surface of the disc is oriented tangential to the earth's surface. The satellite surface has an emissivity of O·3 and is at -18°C. Calculate the net rate at which energy is leaving the satellite.
Assume that:
The average earth surface temperature is 27°C and the earth is black body.

(ii) The satellite is in shadow of the earth and

(iii) The part of the satellite surrounding not occupied by the earth is black and at OK.
Stefan-Boltzmann constant 5·67 x 10-8 W/m2·K4.

7.(c) Differentiate clearly between ventilation and infiltration. Discuss the methods of estimation of infiltrated air.

8.(a) The engine test on a single cylinder four stroke diese1 engine has following observations:
Test duration 1 hr
Bore x Stroke 0·3 m x 0·45 m
Fuel consumption 11·4 kg
Calorific value of fuel 42 MJ/kg
Indicated mean effective pressure 6 bar
Net load on brake 1500 N
Engine rpm 300 rpm
Brake drum diameter 1·8 m
Brake rope diameter 20 mm
Quantity of the jacket cooling water 600 kg
Temperature rise of cooling water 55°C
Quantity of exhaust measured 290 kg
Exhaust gas temperature 420°C
Specific heat of exhaust gas 1·03 kJ/kg-K
Ambient temperature 20°C

Estimate
The indicated power

(ii) The brake power

(iii) The indicated thermal efficiency
Draw up an energy balance sheet

8.(b) In an air-conditioning plant, an air handling unit supplies a total of 4000 m^3/min of dry air which comprises by mass 20% of fresh air at 39°C DBT and 26°C WBT and 80% recirculated air at 24°C DBT and 50% RH. The air leaves the cooling coil at 12°C saturated: Using Psychrometric chart calculate

(i) Total cooling load and

(ii) Room heat gain. Also show the process on Psychrometric chart.

8.(c) Write down the assumptions to analyze a counterflow heat exchanger using LMTD (Log mean temperature difference) method and also write down the expression for LMTD in a counterflow heat exchanger with the help of terminal temperatures.