A closed container filled with hot coffee as shown below is in a room whose air and walls are at fixed temperature much lower than the coffee. Identify all heat transfer process that contributes to cooling of the coffee. Draw schematics, make necessary assumptions (black body, thickness, materials and convection coefficient) and find the heat flux equation and temperature equation at points of heat transfer.

A closed container filled with hot coffee as shown below is in a room whose air and walls are at fixed temperature much lower than the coffee. Identify all heat transfer process that contributes to cooling of the coffee. Draw schematics, make necessary assumptions (black body, thickness, materials and convection coefficient) and find the heat flux equation and temperature equation at points of heat transfer.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.30P

See similar textbooks

Similar questions

Determine the rate of heat transfer per meter length from a 5-cm-OD pipe at 150C placed eccentrically within a larger cylinder of 85 magnesia wool as shown in the sketch. The outside diameter of the larger cylinder is 15 cm and the surface temperature is 50C.
A 0.6-cm diameter mild steel rod at 38C is suddenly immersed in a liquid at 93C with hc=110W/m2K. Determine the time required for the rod to warm to 88C.
3.38 An egg, which for the purposes of this problem is assumed to be a 5-cm-diameter sphere having the thermal properties of water, is initially at a temperature of . It is immersed in boiling water at for 15 min. The heat transfer coefficient from the water to the egg is assumed to be . What is the temperature of the egg center at the end of the cooking period?
2.43 A turbine blade 6.3 cm long, with cross-sectional area and perimeter , is made of stainless steel . The temperature of the root, , is . The blade is exposed to a hot gas at , and the heat transfer coefficient is K. Determine the temperature of the blade tip and the rate of heat flow at the root of the blade. Assume that the tip is insulated.
The heat transfer coefficient for a gas flowing over a thin float plate 3-m long and 0.3-m wide varies with distance from the leading edge according to hc(x)=10x1/4Wm2K If the plate temperature is 170C and the gas temperature is 30C, calculate (a) the average heat transfer coefficient, (b) the rate of heat transfer between the plate and the gas, and (c) the local heat flux 2 m from the leading edge. Problem 1.18
1.21 In an experimental set up in a laboratory, a long cylinder with a 5-cm diameter, and an electrical resistance heater inside its entire length is cooled with water flowing crosswise over the cylinder at and a velocity of 0.8 m/s. For these flow conditions, 20 kW/m of power is required to maintain a uniform temperature of at the surface of the cylinder. When water is not available, air at is used with a velocity of 10 m/s to maintain the same surface temperature. However, in this case, the cylinder surface heat dissipation rate is reduced to 400 W/m. Calculate the convection heat transfer coefficients for both water and air, and comment on the reason for the differences in the values.
Solve for the rate of natural convection heat loss from a flat 1-m square, restaurant grill heated to 227⁰Cin ambient air at 27⁰C ifa) the grilling surface is horizontal facing upc) the grilling surface is horizontal facing down
Hi, can you help me to answer this question using the first law of thermodynamics? On a hot summer day a student turns his fan on when he leaves his room in themorning. When he returns in the evening will the room be warmer or cooler than theneighborouing rooms ? Explain your answer using the first law of thermodynamics.Assume ALL doors and windows are kept closed.
The 4cm thick large copper plate, initially at a uniform temperature of 25oC, is heated by passing it through an oven kept at 400oC. The copper plate remains in the oven for 5 minutes. Calculate the surface temperature of the copper plate when it is taken out of the furnace by taking the heat transfer coefficient h = 200W / m2oC.Properties of copper at room temperature: I want to solution with Biot number
PROBLEM 1Consider an adult human standing in the centre of a closed room. The air and room’swalls, ceiling and floor surrounding the being are at a temperature of 25oC. Assume forthe adult body a temperature of 37oC, a surface area of 1.7m2, an emissivity of 0.95 andthe heat transfer coefficient of 6 W/m2K for natural convection between the air and thebody. Question:(a) Describe the modes of heat transfer between the adult human and theirsurroundings. What are some assumptions that must be made before calculatingthe heat transfer rates?(b) Determine the total rate of heat transfer from the adult into their surroundings.
In a quenching process, a copper plate of 3 mm thick is heated up to 350°C and then suddenly, it is dropped into a water bath at 25°C. (a) Calculate the time required for the plate to reach thetemperature of 50°C. The heat transfer coefficient on the surface of the plate is 28 W/m2 -K. The plate dimensions may be taken as length 40 cm and width 30 cm. (b) Also calculate the time required for infinite long plate to cool to 50°C. Other parameters remain same. (c) Calculate the heat transfer rate loss of the plate when it is at 50°C. Take the properties of copper as: CP = 380 J/kg-K, ρ = 8800 kg/m3 , k = 385 W/m-K
A food product with 80% moisture content in a 10 cm diameter can wants to be frozen. The density of the product is 1000 kg / m³, the thermal conductivity is 1.0 W / (m K), and the initial freezing temperature is -2 ° C. After 14 hours in the freezing medium -30 ° C, the product temperature becomes -10 ° C. Estimate the convection heat transfer coefficient of the freezing medium. Assume the can as an infinite cylinder.