Ex1. A piece of chromium steel of length 7.4cm (density=8780kg/m; k = 50w/mK and specific heat cp = 440j/kgK) with mass 1.27kg is rolled into a solid cylinder and heated to a temperature of 600°C and quenched in oil at 36°c. Show that the lumped capacitance system analysis is applicable and find the temperature of the cylinder after 4min. What is the total heat transfer during this period? You may take the convective heat transfer coefficient between the oil and cylinder at 280w/m2k.

Ex1. A piece of chromium steel of length 7.4cm (density=8780kg/m; k = 50w/mK and specific heat cp = 440j/kgK) with mass 1.27kg is rolled into a solid cylinder and heated to a temperature of 600°C and quenched in oil at 36°c. Show that the lumped capacitance system analysis is applicable and find the temperature of the cylinder after 4min. What is the total heat transfer during this period? You may take the convective heat transfer coefficient between the oil and cylinder at 280w/m2k.

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

See similar textbooks

Similar questions

Water vapor with a flow rate of 20000 kg / h enters the condenser of a power plant at a pressure of 20 kPa and 95% dryness. In the condenser, there is heat transfer to the river water flowing through the pipes. The temperature rise of the river water is limited to 10 ° C to prevent thermal pollution. Since the state of the water at the condenser outlet is a saturated liquid at 20 kPa pressure, what is the flow rate of the cooling water?
An air-conditioning absorption system has an evaporator capacity of 350 kW with a COP of 0.90 operating at a temperature of 25 C with a condensing temperature of 35 C. The same cooling tower was used to reject the heat from the condenser and the absorber operating 45 C & providing 1 kg/s of water plus lithium bromide solution to the generator. Consider the heat rejection ratio of condenser to evaporator is 1.05, Determine the following: 1. Heat given by the generator & the size of condenser in kW 2. Leaving condenser & evaporator enthalpies & the mass of refrigerant water flowing from the generator to the condenser then to the evaporator & to the absorber (using evaporator heat balance). 3. Weight of lithium bromide in kg/s, concentration in percent & enthalpy from the absorber to the generator in kJ/kg 4. Enthalpy from the generator to condenser in kJ/kg (using condenser heat balance) & concentration in percent & enthalpy from generator to absorber…
Steam is used to heat a cylindrical open tank of water until it boils, after which a proportion of the water in the tank is vaporised. The tank has an internal diameter of 1 m and is initially filled with water to a depth of 2 m. At the start of the process, this water is at 19°C and has a density of 998 kg/m3 . It may be assumed that ambient atmospheric pressure is 1 bar and that any effects arising from hydrostatic head can be ignored, as can heat losses from the tank to the surrounding environment. The heating medium is saturated steam at 5 bar, which enters a heating coil at the base of the tank at 5 kg/min, loses heat to the water in the tank and condenses to form saturated liquid condensate at this pressure. Using the steam table supplied: a) Find the temperature (°C) and power rating (kW) of the heater coil. b) Find the boiling point of the water in the tank under these conditions, and the time required to bring the water to this temperature. c) Find the proportion of water…
2 m^3/min of a light oil are to be heated from 20C to 100C (with zero vaporization) in an exchanger using 250 kPa steam of 90% quality. The heat losses to the surrounding air have been estimated to be 5% of the heat transferred from the condensing steam to the oil. If the steam condensate leaves at its saturation point, what mass of steam perhour will be used in the exchanger? For light oil, Specific gravity= 0.88Specific heat= 2.00 kJ/kg-KFor steam at 250 kPa,Saturated liquid: hf= 535.49 kJ/kgvf=0.001067 m^3/kgSaturated vapor: hg= 2716.8 kJ/kgvg= 0.7188 m^3/kg
Water vapor with a flow rate of 20000 kg / h enters the condenser of a power plant at a pressure of 20 kPa and a dryness degree of 95 percent. In the condenser, there is heat transfer to the river water flowing through the pipes. The temperature rise of the river water is limited to 10 C to prevent thermal pollution. Since the state of the water at the condenser outlet is saturated liquid at 20 kPa pressure, what should be the flow rate of the cooling water.
What refrigeration capacity in TOR is required to cool 2000 cfm of air from 85°F to 70°F? If the specific heat ratio (k) and specific gas constant (R) of air are 1.4 and 0.28708 kJ/kg-K, respectively.
Design a hydrocooling unit that can cool fruits and vegetables from 30°C to 5°C at a rate of 20,000 kg/h under the following conditions: The unit will be of flood type that will cool the products as they are conveyed into the channel filled with water. The products will be dropped into the channel filled with water at one end and picked up at the other end. The channel can be as wide as 3 m and as high as 90 cm. The water is to be circulated and cooled by the evaporator section of a refrigeration system. The refrigerant temperature inside the coils is to be -2°C, and the water temperature is not to drop below 1°C and not to exceed 6°C. Assuming reasonable values for the average product density, specific heat, and porosity (the fraction of air volume in a box), recommend reasonable values for the quantities related to the thermal aspects of the hydrocooler, including (a) how long the fruits and vegetables need to remain in the channel, (b) the length of the channel, (c) the water…
The condensing pressure for a Rankine engine is 1 bar (hf= 417.4 kJ/kg). Calculate the net work for 1 kg/s of steam and the thermal efficiency when the steam at the beginning of expansion is at 50 bar and (a) saturated (b) 350°C and (c) 640°C. Note the variation of efficiency and the quality at the end of the expansion.
Calculate the amount of heat to be supplied to generate 10 kg/sec of steam at 12 MPa and 400°C from water at 115°C.
In a power plant steam, steam is continuously extracted from the turbine and in a heat exchanger there is a condensation of the extracted steam. The energy released during condensation of steam is used to operate a heat engine. A heat engine receives thermal energy at a rate of 1200 kJ/min from condensing steam and rejects waste heat to a lake at 25°C at a rate of 850 kJ/min. Determine the lowest possible condensing steam temperature.
A pharmaceutical company plans to install a solid fuel fired boiler for its daily usage. The desired capacity of the steam generation is 1.25 kg per second at pressure of 1.15 MPa and temperature 215oC. Feed water at average temperature of 25oC, is to be fetched from nearby reservoir. The consumption of the solid fuel having calorific value of 25.7 MJ/kg is 375 grams per second. Evaluate the enhancement of efficiency of the boiler if the following accessories are coupled with it. i) Economizer that increases the inlet feed water temperature by 63⁰C and reduces the fuel consumption by 18%. ii) Air-preheater that reduces the fuel consumption by 26%.
Steam is delivered to turbine at 5.4 MPa and 600 degree C. Before condensation at 31 degree C, steam is extracted for feed water heating at 0.6 MPa. The turbine exhaust is 60 degree C. the required values of some state point properties are tabulated below. 7. Determine the quality of steam at the condenser inlet.