Condenser Compressor stage 2 Q2- Find the coefficient of performance for the fallowing cycle and coefficient of performance of simple refrigeration cycle for same temperatures at evaporator and condenser R-134a sat. vapor 20C Mixing chamber Flash chamber Sat. liquid -20°C Compressor stage 1 vaporator

Condenser Compressor stage 2 Q2- Find the coefficient of performance for the fallowing cycle and coefficient of performance of simple refrigeration cycle for same temperatures at evaporator and condenser R-134a sat. vapor 20C Mixing chamber Flash chamber Sat. liquid -20°C Compressor stage 1 vaporator

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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A boiler takes in feed water at 70 °C and generates steam at a pressure of 10 bar and drynessfraction 0.92. The wet steam enters a superheater and emerges with the same pressure at atemperature of 400 °C. If the steam flow rate is 5 tonnes per hour, determine (i) the rate atwhich heat transfer takes place in the boiler and (ii) the rate at which heat transfer takes placein the superheater. State any assumptions you have made in relation to the steady flowequation for the process.
A three-stage compressor receives 500 lps of air at 101 kPaa and 27degrees Celcius, anddischarges at 750 kPaa. Determine a) the power required; b) the pressure at eachintercooler; c) the maximum temperature; and d) the heat transferred in each intercooler. e) What is the discharge temperature of a single-stage compressor operating at the sameintake and discharge temperatures?
A steady-flow, steady-state thermodynamic system receives 1.67 lb/sof a fluid at 4320 psfa and 200°F and discharges it from a point80-ft above the entrance section at 21600 psfa and 600°F. The fluidenters with velocity of 120 ft/s and leaves with a velocity of 40ft/s. During this process, there are supplied 400 Btu/min of heatfrom an external source, and the increase in enthalpy is 2.0 Btu/lb.Determine the work done in horsepower.
Q5/ A surface condenser handles condensate at 70.15 cm Hg when barometer reads 76 cm Hg. Steam entering at 2360 kg/hr requires cooling water at 6.81  102 kg/hr, 10°C. Cooling water leaves condenser at 27.8°C while condenser has mean temperature of 37°C. Air leaks into condenser at 0.3 kg/min. Determine, (i) the mass of vapour going out with air per hour (ii) the state of steam entering.
Answer the other probem (NOT 1C5) use 1C5 as a reference 1.C.5. The refrigerant in an evaporator goes through phase change at a constant temperatureof −30◦C. The rate of vaporization of the refrigerant is 0.15 kg/s. The latent heat of vaporization ofthe refrigerant is 412.1 kJ/kg. Air enters the evaporator at mass flow rate 1.1 kg/s with a temperatureof 45◦C. Assume air has a constant specific heat of 1007 J/kg·K. What is the effectiveness of this heatexchanger? It was found that the convection coefficient of air in the evaporator described in Example 1C.5 is350 W/m2·K, and the heat transfer surface area is 5.1 m2. What is the average convection coefficientof the refrigerant under these conditions? (Note: As the refrigerant is evaporating, it is also flowingin the heat exchanger. And since it is a flowing fluid, it will have a convection coefficient.)
Steam at a pressure of 11 bar and a temperature of 320C is containedin a large vessel. Connected to the vessel through a valve is a turbinefollowed by a small initially evacuated tank with a volume of 0.60 m3.When emergency power is required, the valve is opened and the tankfills with steam until the pressure is 11 bar. The temperature in the tankis then 400C. The filling process takes place adiabatically and kineticand potential energy effects are negligible. Determine the amount ofwork developed by the turbine in kJ.
A steel casting weighing 2 kg has an initial temperature of 500oC; 40 kg of water initiallyat 25oC is contained in a perfectly insulated steel tank weighing 5 kg. The casting isimmersed in the water and the system is allowed to come to equilibrium. What is its finaltemperature? Ignore effects of expansion or contraction, and assume constant specific heatsof 4.18 kJ/kg.oC for water and 0.5 kJ/kg.oC for steel.
An adiabatic piston-cylinder device equipped with aspring maintains the pressure inside at 300 kPa, when thevolume is 0, and in 3 000 kPa, when the volume is 5 m ^ 3. Thedevice connects to a steam supply lineat 1,500 kPa and 200 ° C, and at the beginning the volume of the cylinder is 0.Determine the final temperature (and quality, if applicable) whenthe valve is opened and water vapor is allowed to enter from thesupply to the cylinder, until the pressure inside is equal tothe one on the line. Also determine the total workperformed during this adiabatic filling process.
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Steam enters the condenser of a steam power plant at 20 kPa and aquality of 90 percent with a mass flow rate of 20,000 kg/h. It is to be cooled by water from anearby river by circulating the water through the tubes within the condenser. To preventthermal pollution, the river water is not allowed to experience a temperature rise above10°C. If the steam is to leave the condenser as saturated liquid at 20 kPa, determine(a) the mass flow rate of the cooling water required, and(b) rate of heat loss from the steam
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A single-acting, twin-cylinder 15.25 x 15.25-cm compressor receives saturatedammonia vapor at -18°C and discharges it at 1514.3 kPa. The system is used to produceice at a final temperature of -10°C from water at 27°C. The compressor runs at 450 rpmwith an actual volumetric efficiency of 78%. Assume compression and mechanicalefficiencies to be 82% and 88%, respectively. Calculate the following: (a)capacity ofthe system in tons of refrigeration, (b) brake hp required by the compressor, (c) tons ofice produced per day if compressor runs only 20 hours a day. Assume losses to be 10%of the refrigeration required to produce the ice, and (d) ideal and actual COP.