university of southern california Operations And Supply Chain Management Assignment Help - Microscopic and macroscopic

Question -
K.L.UNIVERSITY
Sophomore Engineering Department
(Division Of Mechanical Engineering)
Assignment questions, 2011-2012(Semester-III)
Course Code: MEC 204 Date of Exam: 09-10-2011
Course Title: ENGG. THERMODYNAMICS Time of Exam: 9.15AM-10.00AM
Course Coordinator: G.L.NARAYANA Max. Marks: 20
NOTE:
                                            (i)       Answer any TWO questions given to you.
                                          (ii)      Ea ...Read More ch question carries 10 marks.
(1)            Differentiate between the following briefly:
(a)   Microscopic and macroscopic approaches in thermodynamics
(b)   Reversible and irreversible processes
(c)    Heat pump and refrigerator
(d)   Low grade energy and high grade energy
(e)    Carnot heat engine and reversed Carnot heat engine.
(2)            Describe the following briefly:
(a)   Absolute thermodynamic temperature scale
(b)   Steady flow energy equation
(c)    Quasi-static process
(d)   Carnot theorem
(e)    Free expansion process
(3)            Justify your answers for the following:
(a)   A process will not occur unless it satisfies both the first and second laws of thermodynamics.
(b)   Zeroth law of thermodynamics forms the basis for temperature measurement.
(c)    Second law of thermodynamics is also called law of degradation of energy or directional law of nature.
(d)   PMM1 and PMM2 are impossible to construct.
(e)    Internal energy is a property of system.
(4)            Substantiate your answers with proper reasoning for the following:
(a)   Some people suffer from nose bleeding and some others experiences shortness of breath at high elevations.
(b)   When a fluid is expanded during constant pressure process, maximum work can be obtained compared to other quasi-static processes.
(c)    The hot air in a conventional oven in which potatoes are being baked can be regarded as a thermal energy reservoir.
(d)   On a hot summer day, a student turns his fan on in his cubicle and closes all wooden doors and windows before he departs in the morning. By evening he returns, his cubicle will be warmer than the neighboring rooms.
(e)    A soft drink can, initially at room temperature, could be modeled as a closed system when it is put in a refrigerator to cool.
(5)            Verify the validity or otherwise for the following cases:
(a)   An engine having thermal efficiency of 25% receives 1200kJ of heat at 400K and rejects 500kJ of heat to one sink at 300K and 400kJ of heat to another sink at 350K simultaneously.
(b)   A refrigeration system operating between -33C and 27C produces 17.6kW of refrigerating effect and rejects heat at the rate of 19.8kW.
(c)    An engine receiving 600kJ of heat and rejecting 400kJ of heat produces 250kJ of output.
(d)   An inventor of a heat engine claims that his engine is 75% efficient which receives heat at 100C and rejects at 25C.
(e)    The energy required will be greater when a certain mass of ideal gas is heated from 325K to 355K at constant pressure compared to constant volume.
(6)            Prove the following statements:
(a)   Both the statements of second law of thermodynamics are equal.
(b)   The efficiency of a reversible heat engine is independent of the nature or amount of the working substance undergoing the cycle.
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