Applied Heat Past Examination Questions

Applied disturb past Examination Questions 1. An Ammonia refrigerator is to produce 2 machine translation of ice per day at -4C from water at 20C. if the temperature range in the compressor is between 25C and -6C, wager provide power required to derive the compressor. Latent Heat of ice = 80 kcal/kg, and specific affectionateness of ice= 0. 5 2. A compressor draws 42. 5 m3 of line of work per minute in the piston chamber, at a compel of 1. 05 kg/cm abs. It is compressed Polytropically pV1. 3=C to a force 4. 2 kg/cm2 abs, before universe delivered to a receiver. Assuming a mechanical qualification of 80% portend a.Indicated horse power b. Shaft horse power, and c. boilers suit iso caloric efficiency. 3. A angiotensin converting enzyme dress appetency turbine has a fixture of 1000rpm and a mean steel ring diam of 60 cm. The nozzles atomic number 18 inclined at 22 to the plane of rotation and the specific henry project is 190 KJ/kg. particularise a. The relative u pper of the locomote at entry, and b. The marque inlet weight down. 4. An engine consumes fuel of calorific value 44MJ/Kg at a appraise of 45tonne/day. It the indicated thermic efficiency is 39% and unveil thermal efficiency is 33%. manoeuver a. The indicated power, b. The brake power, and . The power illogical to friction. 5. The channel in a ships saloon is keep at 19C and is changed twice every hour from the international atmosphere which is at 7C. The saloon is 27m by 15m by 3m high school. deem the kilowatt loading to heat this expression taking the saloon to be at atmospheric Pressure = 1. 013 bar. R for ancestry =0. 287 KJ/kg K. 6. 0. 23kg of variant has an initial pressure of 1. 7 MN/m2 and a temperature of 200C. it is expand to a pressure of 0. 34 MN/m2 correspond to the uprightness pV 1. 35 = Constant. even up the work wobblered during the expansion. expect R = 0. 29 KJ/kg K. 7.The equivalent evapoproportionn of a boiler from and at 100C is 10. 4 kg goer/kg fuel. The calorific value of the fuel is 29800KJ/kg. coiffe the efficiency of the boiler. If the boiler produces 15000 kg of travel per hour at 24 bar from feed water of 40C and the fuel employment is 1650 kg/h, determine the condition of the steam produced. 8. A atomic number 53- cylinder, double play playing steam engine is 250mm bore by three hundredmm cut and runs at 3. 5 rev up/s, steam is supplied at 1035 KN/m2 and the back pressure is 34 KN/m2 and the diagram factor is 0. 81. furbish up the indicated power of the engine. a. If cut glum is at 0. 5 thump, b. If cut withdraw is at 0. 5 dig. 9. Air enters a nozzle with a pressure of 700 KN/m2 and with a temperature of 180C. Exit pressure is 100 KN/m2. The justice connecting pressure and specific strength during the expansion in the nozzle is pV1. 3=Constant. Determine the velocity at function from the nozzle. Take Cp= 1. 006 KJ/kg K and Cv=0. 717 KJ/kg K. 10. A single row, proneness turbine has a mean stigma speed of 215 m/s. Nozzle entry angle is at 30 to the plane of rotation of the blades. The steam velocity from the nozzles is 550 m/s. There is 15% loss of relative velocity due to friction across blades.The living velocity at the proceed is along the axis of the turbine. The steam advert by the turbine is at the evaluate of 700 kg/h. Determine a. The inlet and exit angles of the blades, b. The absolute velocity of the steam at exit, c. The power output of the turbine. 11. The high temperature of a Carnot cycle is 400C and the cycle has a thermal efficiency of 55%. The mickle balancen of the isothermal processes is 2 8 1. Determine for the cycle a. The low temperature, b. The masses ration of the adiabatic processes, c. The boilersuit thermal efficiency. Take r = 1. 4 12.A diesel engine has a conglutination ratio of 141 and an efficiency ratio of 0. 7 when referred to the stemma standard efficiency. The fuel inspiration is 5. 65 kg/h. Take r=1. 4 and calorific val ue of the fuel oil is 44500 KJ/kg. Determine the indicated power developed. 13. The analysis of a fuel oil is 85. 5% carbon, 11. 9% heat content, 1. 6% oxygen and 1% impurities. Calculate the partage of carbon dioxide in the flue vauntses, a. When the quantity of air supplied is the minimum for complete blaze, and b. When the excess air over the minimum is (i) 25% (ii) 50% iii) 75% 14. In an air compressor the air is compressed to the law pVn= unvarying. The compressor takes in 105 m3/min of air at 1. 0 bar 27C. If the pressure ratio is 5 to 1, work up a. The index of coalescency, b. Power absorbed by the compressor. 15. A single acting opposed piston 6 cylinder two cut engine have mechanical efficiency of 86% when running at 105 rpm with mean proceedsive pressure of 7. 24 bar, produces brake power of 4326 kW. The mass of the top piston with its connecting parts is 25% great than that of bottom piston and the combined stroke is 2340 mm.If the stroke of piston varies mutua lly as the masses of the reciprocating parts. Calculate (i) The stroke of the top and bottom pistons, (ii) The cylinder diameter. 16. The mass analysis of a fuel is 86% carbon, 11. 5% total heat and 2. 5% oxygen. If for complete combustion 25% excess air is supplied per kg of fuel turn offt, answer for a. The mass of flue gases, b. Volume of air at 1. 0 bar and 15C. Take R for air = 0. 287 kJ/kgh. 17. The diameter of an air compressor cylinder is 140 mm, the stroke is 180 mm, and the clearance volume is 77cm. he pressure in the cylinder at the beginning of the stroke is 1. 0 bar and during delivery is constant at 4. 8 bar. winning the law of coalescence as pV1. 25=Constant, take care the distance go by the piston during the delivery period and express this as figure of the stroke. 18. A turbine plant consists of H. P. and L. P. stages and is supplied with steam at 15 bar 300C. The steam is spread out in the H. P. and leaves at 2. 5 bar 0. 97 run dry. Some of the steam is b led off to the feed heater and remaining passes to L. P. where it is expanded to 0. 15 bar 0. 84 dry.If the same quantity of work transfer takes place in each unit, image the amount of steam bled off expressed as per centumage of the steam supplied. 19. 7. 08 liters of air at a pressure 1. 79 bar and temperature of 333C is expanded according to the law pV 1. 3 = constant and the final pressure 1. 206 bar, calculate a. Volume at the end of expansion, b. Work transfer from the air and, c. The temperature at the end of expansion. 20. move leaves the nozzle and enters the blade wheel of a single stage impulse turbine at a velocity of 840 m/s and at an angle of 20 to the plane of rotation.The blade velocity is 350 m/s and the exit angle of the blade is 2512. Due to friction the steam looses 20% of its rotational velocity across the blades, calculate a. The blade inlet angle and, b. The magnitude and the direction of absolute velocity of steam at exit. 21. In a Freon-12 refrigerating p lant, Freon leaves the optical condenser with a specific heat content of 50kJ/kgK. The pressure in the evaporator is 1. 826 bars and the cold leaves the evaporator at this pressure at a rate of 0. 4 Kg/s and a temperature of 0C. Calculate a. Dryness fraction of Freon at inlet of the evaporator, b.The refrigerating effect per minute. 22. A glass tube of uniform bore is closed at on end and open at the other. It contains air imprisoned by a column of mercury 42. 7 mm long. When the tube is held vertically with close end at the bottom, the length of the air column is 227. 6mm. victorious 1mm of mercury = 133. 5N/m2 and atmospheric pressure = 101. 5 kN/m2. Calculate the length of the air column if the tube is held vertically with the closed end at the top. 23. A single acting gas engine of bore 190 mm and stroke 380 mm has an indicated power of 13 kW when developing brake power of 9 kW there being 125 explosions per minute.The consumption of gas of calorific value 1. 76 MJ/m3 is 6. 8m3/hour. Calculate the mechanical and indicated thermal efficiencies, and the mean effective pressure. 24. A six cylinder, four stroke, internal combustion engine is required to develop a brake of 176 kW chthonic the following conditions Speed 200rev/min, brake m. e. p. 8 bars, stroke/bore ratio 1. 25/1. Break specific fuel consumption 0. 262 Kg/KWh. Calculate- a. The cylinder dimensions, and b. Fuel consumption kg/h 25. blow dioxide leaves a refrigeration condenser with a total heat of 156kJ/kg.After throttling it passes through the evaporator from and it leaves with a dryness fraction of 0. 98. At the evaporator pressure the liquid heat is 12kJ/kg and the latent heat is 280kJ/kg. If 13. 8 kg of refrigerant circulates per minute, calculate- a. The dryness fraction at the inlet to the evaporator, and b. The heat absorbed in the evaporator in 24 hours. 26. Steam is generated from feed water at a temperature of 93. 3 C as follows In plant A the steam generated is 17. 25 bar dry sat urated. In plant B the steam generated is 17. 25 bar 0. 9 dry and, In Plant C the steam generated is 17. 5 bar 82C super heat. Calculate the percentage change in the consumption using plant A as the base. 27. A hydrocarbon fuel cell is completely burned with 12. 5 percent excess air. Calculate the Volume of air utilise to burn 1Kg of fuel, metric at 1. 01 bars and 18C. Air contains 23 percent oxygen by mass. atomic mass relationship Hydrogen=2, Carbon=12, Oxygen=16. 28. An oil engine has a volumetric compression ratio of 131. At the commencement of compression the air in the cylinder is at 1 bar and 15. 6C. Calculate the temperature and pressure at the end of compression if the index of compression is 1. 8. 29. A single acting air compressor working without clearance has a 220mm bore and 200mm stroke. The suction conditions atomic number 18 1 bar 27C and running speed is 10 rev/sec. if compression is according to the law pV1. 3=Constant and the sort out pressure is 10 bar. Calc ulate, a. The mass of air compressed per hour, and b. The discharge temperature. 30. Calculate the final temperatures and final total heat of both (a) and (b). a. Water at 65. 6 C having a mass of 45. 36 kg is cooled by placing 4. 536 kg of ice at -8. 9C into the water. b. Water at 65. 6C having a mass of 54. 1 kg is cooled by addition of 22. 68 kg of water at 26. 7C. 31. An impulse steam turbine operates at 50rev/sec. The mean blade tip diameter is 0. 6m. The blade exit angle is 30 and the velocity of the steam relative to the blade at blade exit is 300 m/s. Calculate or determine by any(prenominal) other means the kinetic vigour of steam leaving the blades per kilo of steam course. 32. A perfect gas at 3. 1 bar and 30C is compressed according to the law pV1. 3=constant until its temperature increases to 215C. Sketch the process on a p-V diagram and calculate a.The pressure at the end of compression. b. The changes in enthalpy and internal energy per kilogram of gas. 33. In an ideal constant volume cycle the temperature at the beginning of compression is 50C. the volumetric compression ratio is 51. If the heat supplied during the bible is 930 KJ/Kg of working fluid, calculate a. The maximum temperature attained on the cycle, b. Work done during the cycle/kg of working fluid, and c. The thermal efficiency of the cycle. Take ?=1. 4 and Cv= 0. 1717 KJ/Kg K. 34. A fuel has a mass analysis of carbon 87 percent, hydrogen 5. percent and remainder ash. The calorific value of carbon and hydrogen are 34MJ/kg and 145 MJ/kg respectively. Calculate for one kilogram of fuel a. The calorific value, b. The mass of exhaust gas if 35 percent excess air is supplied. When burning fuel, why is excess air used? Air contains 23 percent oxygen by mass Atomic mass relationships hydrogen=1, oxygen=16, carbon=12. 35. One kilogram of dry saturated steam at 4 bars is contained in a cylinder fitted with a piston. The steam rejects 320 KJ of heat energy at constant pressure is 1. 4 bar s. Calculate a.The condition of the steam on closing of cooling at constant pressure, b. The condition of the steam on pass completion of cooling at constant volume, and c. The quantity of heat energy rejected during constant volume cooling. 36. A steam turbine which operates at 50rev/s has a mean blade-ring diameter of 1m at a certain stage. The blades are designed for 50 percent reaction and have the exit and inlet angles at 30 and 50 respectively. The turbine is supplied with steam at the ratio of 166. 67kg/s and the stage efficiency is 85 percent. Calculate or determine by any other means a.The power output of the stage, and b. The specific enthalpy drop in the stage. 37. In Ammonia refrigeration plant the refrigerant leaves the condenser at 22C as saturated liquid. The evaporator pressure is 2. 077bar and refrigerant leaves the evaporator 0. 98 dry saturated. For a cooling load of 40kW, calculate a. The rate of circulation of the refrigerant (kg/s), b. The effective swept vol ume of the compressor (m3) if its speed is 1 rev/s. 38. A copper bar of 75mm diameter, 13m long is heated by a direct current flowing through the bar. The steady electrical comment to the bar is 500W.Assuming the bar is well-insulated and neglecting conduction heat losses at the leads, calculate the wires taken for the temperature of the bar to increase from 5C to 365C. 39. A single stage double acting air compressor deals with 18. 2m3 of air per minute measured at conditions of 1. 61325 bar 15C. The condition at the beginning of compression is 0. 965 bar 27C and the discharge pressure is 4. 82 bars. The compression is according to the law pV1. 32=constant. If the mechanical efficiency of the compressor is 0. 9 calculate the input power required to drive the compressor. 40.In a steady flow process the working fluid enters and leaves a horizontal governing body with trifling velocity. The temperature drop from inlet to outlet is 480C and the heat losses from the system are 10KJ/kg of fluid. Determine the power output from the system for a fluid flow of 1. 7kg/s. For fluid Cp=900 J/kgK. 41. A four stroke single cylinder engine working on constant volume cycle, develops 7. 5 KW(Brake) at 60 rev/s, the mechanical efficiency being 0. 8. The pressure at the beginning of compression is 0. 97 bar. The engine has a volumetric compression ratio of 7 and the maximum pressure reached in the cycle is 34 bar.If both compression and expansion is according to the law pV1. 38=constant. Calculate a. The indicated mean effective pressure, and b. The diameter of the cylinder if stroke/bore ratio is 1. 25. 42. A boiler generates steam at 40 bar 400C and supplied to a steam turbine at the rate of 14 kg/s. due to frictional and heat losses the steam at the turbine inlet is at 37 bar 350C. If the steam velocity leaving the boiler is 30 m/s and the change in the kinetic energy of steam is negligible. Calculate a. The diameter of the steam bring pipe, and b. The heat loss from the s team supply pipe.