A lumped sphere has an initial temperature Ti = 0 oC and the following properties: A...
A lumped sphere has an initial temperature Ti = 0 oC and the following properties: A = 1 m2 , m = 0.1 kg, c = 100 J/(kg oC). Suddenly, the sphere surface has been exposed to a uniform heat flux qw = 30000 W/m2 and also exposed to convection to a cold air that has h = 50 (W/m2 oC) and Tꝏ = 0 oC. If the sphere behavior is described by dT/dt + β T = λ ; Find the following: A) β B) λ C) Time constant τ D) Steady state temperature Tss. If an array of fins with specifications At = 4 m2 and ηo = 0.9 has been attached to the sphere surface, find the following: E) New time constant τ. F) New steady state temperature Tss G) the steady state temperature Tss if h = 0 (sphere receives heat flux qw but without being cooled by surrounding fluid).
Homework Answers
Add Answer to:
A lumped sphere has an initial temperature Ti = 0 oC and the
following properties: A...
7. (20 pts) A sphere with 30 mm in diameter initially at 800 K is quenched...
7. (20 pts) A sphere with 30 mm in diameter initially at 800 K is quenched in a large bath having a constant temperature of 320 K with a convection heat transfer of 75 W/m2.K. The thermophysical properties of the sphere material are: p=400 kg/mº, c=1600 J/kg-K, and k=1.7 W/mK. (Use characteristic length Lc=VIA to determine applicability of lumped method; Use radius of the sphere for one term approximation) a) Calculate the time required for the surface of the sphere...
3. The wall shown in the figure below has thickness L 0.25 m and uniform thermal...
3. The wall shown in the figure below has thickness L 0.25 m and uniform thermal conductivity k-1 W/mK. It is exposed to circulating fluid on the surface at x = L, where the temperature ofthe fluid is T-= 30°C and the convection coefficient is h = 4 W/m2.K. The surface at x = 0 is maintained at constant temperature T-20 °C. Assume ID heat flux, and that the system is at steady state a) b) Determine the temperature distribution...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A current is passed through the wire, resulting in a volumetric heat generation of q - 1.5 x 108 W/m3. The convection coefficient is h - 500 W/m2 - K, and the properties of the wire are ρ-8000 kg/m3, Cp-500 J/kg-K, and...
Consider a 34 cm thick concrete wall with a thermal conductivity of 0.82 W/m·K. The temperature...
Consider a 34 cm thick concrete wall with a thermal conductivity of 0.82 W/m·K. The temperature of the left surface is held constant at 42°C, whereas the right face is exposed to a flow of 12°C air with a convection heat transfer coefficient of 23 W/m2·K. Neglecting heat transfer by radiation, find the right wall surface temperature and the heat flux through the wall.
1: A horizontal, opaque flat surface at a steady-state temperature of 77C is exposed to an...
1: A horizontal, opaque flat surface at a steady-state temperature of 77C is exposed to an airflow having a freestream temperature of 27C with a velocity of 15 m/s, and a length of 1 m along the flow direction. The emissive power of the surface is 628 W/m2 , the irradiation from surroundingsis 1380 W/m2 , and the reflectivity is ?=0.40. (a) Determine the absorptivity (?) of the surface. Ans: 0.6 (b) Determine the net radiation heat transfer rate for...
blem 4 (20 pts) A square chip that is 12.7mm on a side has a maximum allowable chip operating temperature -75°C. To dissipate heat produced in the chip, a 4 x 4 array of copper (k-400 W/m.K) pin fins...
blem 4 (20 pts) A square chip that is 12.7mm on a side has a maximum allowable chip operating temperature -75°C. To dissipate heat produced in the chip, a 4 x 4 array of copper (k-400 W/m.K) pin fins is proposed to be etallurgically joined to the outer surface of the chip. The convection coefficient is h-250 W/m'K and ambient air mperature isTo-20°C. The pin fin dimeter is D,-1.5mm and length is L,-16mm. Assuming steady-state uniform chip temperature Te-75°C and...
Question 11 (15 points) The wall of a liquid-to-gas heat exchanger has a surface area on...
Question 11 (15 points) The wall of a liquid-to-gas heat exchanger has a surface area on the liquid side of 1.8 m2 (0.6 m * 3.0 m) with a heat transfer coefficient of 255 W/m2 K. On the other side of the heat exchanger wall a gas flows, and the wall has 96 thin rectangular steel fins 0.5 cm thick and 1.25 cm high (k = 3 W/m K) as shown in the figure below. The fins are 3 m...
A large plane wall has a thickness L = 50 cm and thermal conductivity k =...
A large plane wall has a thickness L = 50 cm and thermal conductivity k = 25W/m·K. On the left surface (x = 0), it is subjected to a uniform heat flux ?̇0 while the surface temperature T0 is constant. On the right surface, it experiences convection and radiation heat transfer while the surface temperature is TL = 225°C and the surrounding temperature is 25°C. The emissivity and the convection heat transfer coefficient on the right surface are 0.7 and...
One end of a long rod 3 cm in diameter is inserted into a furnace with the
One end of a long rod 3 cm in diameter is inserted into a furnace with the (3 outer end projecting into the outside air. Once the steady state is reached the temperature of the rod is measured at two points, 15 cm apart and found to be 140°C and 100°C, when the atmospheric air is at 30°C with convection coefficient of 20 W/m2.K. Calculate the thermal conductivity of *.the rod material Consider a stainless steel spoon(k = 15.1 W/m.K), partially...
Supplemental Problem 2.003 A large plate of thickness 2L is at a uniform temperature of Tỉ-190°C,...
I will rate. Thanks so much
Supplemental Problem 2.003 A large plate of thickness 2L is at a uniform temperature of Tỉ-190°C, when it is suddenly quenched by dipping it in a liquid bath of temperature To Heat transfer to the liquid is characterized by the convection coefficient h. Assume x = 0 corresponds to the midplane of the wall -20°C (a) If h = 100 w/m2, K, what is the heat flux atx = L and t = 0?...
7. (20 pts) A sphere with 30 mm in diameter initially at 800 K is quenched in a large bath having a constant temperature of 320 K with a convection heat transfer of 75 W/m2.K. The thermophysical properties of the sphere material are: p=400 kg/mº, c=1600 J/kg-K, and k=1.7 W/mK. (Use characteristic length Lc=VIA to determine applicability of lumped method; Use radius of the sphere for one term approximation) a) Calculate the time required for the surface of the sphere...
3. The wall shown in the figure below has thickness L 0.25 m and uniform thermal conductivity k-1 W/mK. It is exposed to circulating fluid on the surface at x = L, where the temperature ofthe fluid is T-= 30°C and the convection coefficient is h = 4 W/m2.K. The surface at x = 0 is maintained at constant temperature T-20 °C. Assume ID heat flux, and that the system is at steady state a) b) Determine the temperature distribution...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A current is passed through the wire, resulting in a volumetric heat generation of q - 1.5 x 108 W/m3. The convection coefficient is h - 500 W/m2 - K, and the properties of the wire are ρ-8000 kg/m3, Cp-500 J/kg-K, and...
blem 4 (20 pts) A square chip that is 12.7mm on a side has a maximum allowable chip operating temperature -75°C. To dissipate heat produced in the chip, a 4 x 4 array of copper (k-400 W/m.K) pin fins is proposed to be etallurgically joined to the outer surface of the chip. The convection coefficient is h-250 W/m'K and ambient air mperature isTo-20°C. The pin fin dimeter is D,-1.5mm and length is L,-16mm. Assuming steady-state uniform chip temperature Te-75°C and...
Question 11 (15 points) The wall of a liquid-to-gas heat exchanger has a surface area on the liquid side of 1.8 m2 (0.6 m * 3.0 m) with a heat transfer coefficient of 255 W/m2 K. On the other side of the heat exchanger wall a gas flows, and the wall has 96 thin rectangular steel fins 0.5 cm thick and 1.25 cm high (k = 3 W/m K) as shown in the figure below. The fins are 3 m...
I will rate. Thanks so much
Supplemental Problem 2.003 A large plate of thickness 2L is at a uniform temperature of Tỉ-190°C, when it is suddenly quenched by dipping it in a liquid bath of temperature To Heat transfer to the liquid is characterized by the convection coefficient h. Assume x = 0 corresponds to the midplane of the wall -20°C (a) If h = 100 w/m2, K, what is the heat flux atx = L and t = 0?...
Most questions answered within 3 hours.
-
Where is the error in this code sequence?
String s1 = "Hello";
String s2 = "ello";...
asked 11 months ago -
Financial data for Joel de Paris, Inc., for last year
follow:
Joel de Paris, Inc.
Balance...
asked 11 months ago -
Consider this reaction:
Al2(SO4)3 (aq)+ BaCl3
(aq) Al2Cl6 (aq)- +
3BaSO4(s) . What is the...
asked 11 months ago -
Suppose that Savneet is considering increasing her
recent random sample from 20 car rentals to 40...
asked 11 months ago -
Trucks arrive at an unloading terminal at an average rate of 120
per hour.
Trucks arrive...
asked 11 months ago -
Why are methanol and ethanol completely soluble in water while
octanol is not very little soluble....
asked 11 months ago -
A facilities manager at a university reads in a research report
that the mean amount of...
asked 11 months ago -
When the CuSO4 is rehydrated by adding water to the anhydrous
compound, is this an endothermic...
asked 11 months ago -
A ray of sunlight is passing from diamond into crown glass; the
angle of incidence is...
asked 11 months ago -
A block of mass 0.249 kg is placed on top of a light, vertical
spring of...
asked 11 months ago -
how do the kidneys compensate in the presences of acidosis
a) trigger hyperventilate
b) reserve acid...
asked 11 months ago -
Question 501 pts
The rental rate of capital to the firm increases. Which of the
following...
asked 11 months ago