Reference no: EM13942018
The fire brick of Example 12.10 is used to construct the walls of a brick oven. The irradiation on the inte- rior surface of the wall is G = 50,000 W/m2 and has a spectral distribution proportional to that of a black- body at 2000 K. The temperature of the gases adjacent to the inner wall of the oven is 500 K, and the convec- tion heat transfer coefficient is 25 W/m2. Find the wall surface temperature if the heat loss through the wall is negligible. If the brick wall is 0.1 m thick and of thermal conductivity kb = 1.0 W/m · K, and is insulated with a 0.1-m-thick layer of thermal conductivity ki = 0.05 W/m · K, what is the steady-state interior
(a) Determine the total emissivity s of the sample.
(b) Determine the total absorptivity a of the sample for irradiation from the enclosure walls.
(c) Perform an energy balance on the sample and determine the laser irradiation, Glaser, required to maintain the sample at Ts = 2000 K.
(d) Consider a cool-down process, when the laser and the inert gas flow are deactivated. Sketch the total emissivity as a function of the sample temperature, Ts(t), during the process. Identify key features, including the emissivity for the final condition (t l 00).
(e) Estimate the time to cool a sample from its operat- ing condition at Ts(0) = 2000 K to a safe-to-touch temperature of Ts(t) = 40°C. Use the lumped capacitance method and include the effect of con- vection to the inert gas with h = 50 W/m2 · K and T00 = Tenc = 300 K. The thermophysical properties of the sample material are p = 3900 kg/m3, cp = 760 J/kg · K, and k = 45 W/m · K.
|
Prepare the adjusting entries
: Prepare the adjusting entries that were made. Credit account titles are automatically indented when the amount is entered. Do not indent manually.
|
|
Accounts receivable-inventory are some of liquid assets
: Critically discuss the following view: “Accounts receivable and inventory are some of the most liquid assets a firm owns and its market value is typically fairly close to book value. Even so, in the eyes of many lenders, these assets make for inadequ..
|
|
Name the factors that affect economic development
: Name the factors that affect economic development in some countries
|
|
Operations of the global company
: Subject: You are provided with a briefing on the operations of the global company "Enterprise rent-a-car" in the the Marketing kit folder.
|
|
Determine the total absorptivity
: If W = 0.10 m and the coolant is water with a flow rate of mc = 0.1 kg/s, is it reasonable to assume a uniform bottom surface temperature Tc?
|
|
Describe an optimal inventory policy
: The Treknotrics store begins each week with 300 phasers in stock. This stock is depleted each week and reordered. If the carrying cost per phasers is $38 per year and the fixed order cost is $75, what is the total carrying? What is the restocking cos..
|
|
Which bond offers higher expected compound rate of return
: A bond fund manager has a five-year time horizon, and is considering two bonds. The first is a 15-year to maturity bond with a 5.75% coupon rate, paid annually. The price of this bond today is 100% of face value. The second bond is a 20-year to matur..
|
|
What is the amount of the overstatement or understatement
: Elliott Corp. failed to record accrued salaries for 2011, $2,000; 2012, $2,100; and 2013, $3,900. What is the amount of the overstatement or understatement of Retained Earnings at December 31, 2014?
|
|
Description of the requirements for good leadership
: Leadership undergraduate essay - A short description of the requirements for good leadership. Describe the ways in which you believe you meet these requirements and what you believe other people could learn from you as a leader
|