Power Engineering 4th Class - Unit A2 Review Exam Questions And Answers

(4-096-1.1) Large areas, such as warehouses, are usually heated by: Select one: a. Unit heaters b. Radiators c. Convectors d. Open heaters e. Space heaters - ANS a (4-019-3.8) How much heat must be supplied to 200 kg of water at 20°C to make steam at 850 kPa abs and 87% dry? Select one: a. 2039.4 kJ b. 407 880 kJ c. 1774.28 kJ d. 424 627.98 kJ e. 484 507.6 kJ - ANS e (4-018-2.6) Convert -6°C to °F. Select one: a. 30.4°F b. 28.5°F c. 21.2°F d. 18.6°F e. 16.7°F - ANS c (4-020-3.2) A substance that cannot be decomposed into other substances by chemical means is: Select one: a. a Mixture b. a Compound c. a Solution d. an Atom e. an Element - ANS e (4-019-3.4) A boiler furnace releases 10 400 kJ of heat for each kg of fuel burned and produces dry saturated steam at 14 000 kPa abs. from feedwater at 200°C. How many kg of steam will be produced for each kg of fuel burned if the boiler has an efficiency of 66%? Select one: a. 3.546 b. 3.845 c. 4.875 d. 5.754 e. 6.854 - ANS b (4-019-1.6) Steam containing water particles in suspension is defined as: Select one: a. Dry steam b. Theoretical steam c. Wet steam d. Sub-cooled steam e. Superheated steam - ANS c (4-019-1.3) How much heat must be absorbed by 63 kg of ice at 0°C to convert it to saturated steam at 100°C. Specific heat of water is 4.2 kJ/kg K. Latent heat of fusion of ice is 335 kJ/kg. Latent heat of evaporation of steam is 2257 kJ/kg. Select one: a. 35 490 kJ b. 21 775 kJ c. 53 107 kJ d. 189 756 kJ e. 273 097 kJ - ANS d When is hot oil an ideal heat transfer fluid? Select one: a. when high temperature, high pressure process fluids are needed b. when low temperature process fluids are needed at high pressure c. when glycol is too expensive d. when high temperature process fluids are needed at low pressure - ANS d (4-018-4.5) When the temperature of an object is increased, its change in length is proportional to its: Select one: a. Initial length and initial temperature. b. Cross-sectional area and temperature. c. Volume and temperature increase. d. Initial length and temperature increase. e. Initial temperature, but inversely proportional to its length. - ANS d (4-018-2.2) In the First Law of Thermodynamics, heat supplied = increase in internal energy + ____________: Select one: a. Energy supplied. b. Energy absorbed. c. Work input. d. Work done. e. Power output. - ANS d (4-020-3.4) Any material made up of distinct elements, compounds, or both, that are not chemically combined with one another, is a: Select one: a. Solid b. Mixture c. Molecule d. Crystal e. Compound - ANS b (4-018-4.1) Which of the following statements is TRUE? Select one: a. In general, coefficients of expansion of solids are greater than those of liquids. b. Liquids do not contract when cooled. c. The Coefficient of Expansion for a liquid changes if the liquid temperature changes d. Solids contract when heated. e. Water will only expand when its temperature is increased. - ANS c (4-018-5.5) _____ refers to the transfer of heat via electromagnetic waves. Select one: a. Convection b. Transmission c. Conduction d. Induction e. Radiation - ANS e (4-019-3.6) Calculate the boiler efficiency if the heat supplied to the steam is 26 880 kJ per kg of fuel burned and the heating value of 1 kg of fuel is 32 000 kJ. Select one: a. 72% b. 78% c. 84% d. 87.7% e. 89.35% - ANS c (4-018-1.1) ________ is the temperature at which all molecular movement ceases. Select one: a. 0o Celsius b. 0o Fahrenheit c. Absolute zero d. -273 Kelvin e. -460o Rankine - ANS c (4-020-2.8) If a substance goes through a process that changes its composition so that it is no longer the same substance, then the substance has undergone a: Select one: a. Physical change b. Heterogeneous change c. Homogeneous change d. Chemical change e. Mechanical change - ANS d An example of a two-phase heat transfer fluid is Select one: a. petroleum b. glycol/water c. anhydrous ammonia d. heat transfer oil - ANS c (4-018-5.4) The transfer of heat involving the movement of a fluid is defined as: Select one: a. Conduction b. Convection c. Radiation d. Flux e. Thermo-circulation - ANS b (4-018-4.2) When the temperature of an object is raised, its increase in surface area is proportional to its: Select one: a. Initial length and final temperature. b. Initial area and temperature rise. c. Volume and initial temperature. d. Initial length and temperature rise. e. Shape. - ANS b