The temperature of air in a duct is measured by a thermocouple as shown. It's to find the he...
A thermocouple is used to measure the temperature of hot air flowing in a duct whose walls are maintained at Tw = 500 K. The thermocouple shows a temperature reading of Tt h = 850 K. Assuming the emissivity of the thermocouple junction to be 0.6, and the convection heat transfer coefficient to be 60 W/m2 · K, (a) draw the thermal resistance network, and (b) determine the actual temperature of the air.
3. A thermocouple is used to measure the surface temperature of an object. The center of a thermocouple bead of diameter D-100 μm is positioned at a distance 10 μm from the surface of interest. The two thermocouple wires, each of diameter d = 1 mm and length L-250 mm, are held by a large manipulator that is at a temperature of Tm-25 °C. The thermal conductivities of the Nicrosil and Nisil thermocouple wires are Kvic respectively. We can neglect...
The temperature of a flowing gas is to be measured with a thermocouple junction and wire stretched between two legs of a sting, a wind tunnel test fixture. The junc- tion is formed by butt-welding two wires of different material, as shown in the schematic. For wires of diame- ter D = 125 pm and a convection coefficient of h = 700 W/ m K, determine the minimum separation distance between the two legs of the sting, L=L +L, to...
Problem 5: The temperature of air flowing through a 25-cm-diameter duct whose inner walls are at 320° C is to be measured using a thermocouple soldered in a cylindrical steel well of 1.2-cm OD with an oxidized exterior, as shown in the accompanying sketch. The air flows normal to the cylinder at a mass velocity of 17,600 kg/h m1 . If the temperature indicated by the thermocouple is 200°C, estimate the actual temperature of the air Air 17,600 kg/h m2...
Problem Wall with Strip Heater The air inside a chamber is measured to be 50C and used to convectively heat a wall (h 20 w/m2 K). The wall (thermal conductivity of 4 W/m K) is 200 mm thick and has a uniform heat generation of 1000 W/m2. To prevent any heat generated within the wall from being lost to the outside of the chamber a very thin electrical strip heater is placed on the outer wall to provide a uniform...
Problem 2. (20 pts) As shown in the figure, uniform generation occurs inside the spherical core with a radius n due to reactive heating at a rate of q 10 W/m3. The thermal conductivity of the reactive material is 20 Wm. K. The spherical shell 1Sr is made of stainless steel (s.s.) with a thermal conductivity k2 -15 W/m K. Given 0.5 m and k2 72=0.6 m, water flows outside to cool the s.s. shell at To-25°C and h =...
Problem 1 (25 points) In an experiment to measure heat transfer coefficients, a very thin foil of low emissivi attached to a slab of material with low thermal conductivity. The other surface of the metal foil is exposed to convection heat transfer by fluid flowing over the foil surface. The slab on which the metal foil is attached has a thickness of 30 mm and a thermal conductivity of 0.023 W/m K in a condition where the surrounding room temperature...
Homework 7 heat transfer 2018-20 1) A horizontal tube of 12.5-mm dimeter with an outer srface temperature of 240°C is placed in a room with an air temperature of 20°C. Estimate the heat transfer rate per unit length of the tube due to free convection. 2) Air at -10°C flows at 10 m/s over the roof plate of two 5m length rooms whose air is at Too-200C. The roof plate is 0.20-m thick concrete (k = 0.6 w/ m. K)....
i need help on number3 lelmperaturein the luid as a function of r, the distance from the descne t re? What are the boundary conditions? The thermal conductivity k of the fluid is considered center of the sphe constant. The temperature of the sphere constant at Ta boundary is constant at Tr. and the temperature far from the fluid is (b) Determine the temperature profile in the fluid. (c) From the temperature profile, obtain an expression for the heat flux...
summarizr the followung info and write them in your own words and break them into different key points. 6.5 Metering Chamber: 6.5.1 The minimum size of the metering box is governed by the metering area required to obtain a representative test area for the specimen (see 7.2) and for maintenance of reasonable test accuracy. For example, for specimens incorporating air spaces or stud spaces, the metering area shall span an integral number of spaces (see 5.5). The depth of...