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# Convection

Convection is the transfer of heat from one region to another through the motion of fluids. Convection is the most common form of heat transfer. Convection can happen in one of two ways.

The first way of convection is forced convection. This occurs when a fluid is forced to flow over the surface by an external source. The motion which is created is an artificially induced convection current. An example of this type of convection is when a fan is blowing on a hot surface to cool it down faster.

The second way of convection is free convection, also referred to as natural convection. This is when the fluid movement is caused by the variations of temperature in the fluid. For example, when the fluid touches a warm surface, the molecules scatter which causes the fluid to be less dense. The colder fluid gets more dense and will sink. Therefore the more hot volume transfer heat towards the cooler volume of that fluid.

### Transient convection problem that utilizes dimensionless numbers

A 10 cm thick pure gold plate is initially at 85ËšC. Both top and bottom boundary surfaces are exposed to an ambient gas at 15ËšC with a heat transfer coefficient of h=400 W/C-m^s Calculate the center temperature at t = 6 minutes after the start of cooling.

### Heatloss In Copper Pipe

Calculate the rate of heat loss in a copper pipe with length 10m and diameter 25mm, due to convection.

### There is a device which works as heat of pump

There is a device which works as heat of pump. This device is able to heat the air at 1 degree per second. The velocity of hot air is 0.5 m/sec. The professor is placing an alluminium cup full of water. The problem is, how long its going to take the hot air from heating pump to rise the water from 25 deg to 34 deg. You are

### Forced Convection Temperatures

The temperature of a gas stream is measured by a thermocouple whose junction can be approximated as a 1.2mm diameter sphere. The properties of the junction are: K = 40.5 W/m*k p= 7950 kg/m^3 Cp= 345 J/kg*k The heat transfer coefficient between the junction and the air where h= 250 W/m^2 * K Determine how long

### Ideal Gases and Cooling Rates

Air at a pressure of 6000 N/m^2 and temperature of 300 degrees Celsius is flowing with a velocity of 10m/s over a flat plate 0.5m long. Estimate the cooling rate per unit width of the plate needed to maintain it a surface temperature of 25 degrees Celsius. Consider air to be an ideal gas. How does this cooling rate change if the

### Airplane - Heat Problem

Please view attached heat problem. I am having trouble understanding the cylinder part/ and should be used to find the temperature. any help would be appreciated. thanks Assume that the body of an airplane is considered as a 20-m long hollow cylindrical structure made up of unknown composite material. The plane body has insi

### Thermal Conductivity in an Oven Wall

The composite wall of an oven consists of three materials, two of which are of known thermal conductivity, kA = 20 W/m?K and kC = 50 W/m?K, and known thickness, LA = 0.30 m and LC = 0.15 m. The third material, B, which is sandwiched between materials A and C, is of known thickness, LB = 0.15m but the thermal conductivity kB is

### Modes of Heat Transfer

Describe the various modes of heat transfer and the basic principle behind them.

### Sunk Costs, Relevant Cost

Please see attachment. 6. Pat, a Pizzeria manager, replaced the convection oven just six months ago. Today, Turbo Ovens Manufacturing announced the availability of a new convection oven that cooks more quickly with lower operating expenses. Pat is considering the purchase of this faster, lower operating cost, convection ove

### Unit Length Heat Loss and Describing a Thermal Circuit

Please see the attached file for the fully formatted problem(s). Find unit length heat lost and describe the thermal circuit. Copper pipe inside radius r1 = 1cm And thickness of pipe = 0.3 cm So pipe outside radius r2 =1.3cm Thickness of insulated material = 1cm Radius of pipe with insulation r3 =2.3cm Thermal conduct

### Basic concepts -- conduction, convection, radiation

I'm having trouble in my Heat Transfer class and need a better overall understanding of Heat concepts. Please help me grasp the following four things about this assignment: 1) Basic concept this assignment is related to 2) Key equation/formula needed for this assignment 3) Any other basic fundamental concept(s) needed for t

### Natural Convection

Please see the attached file for the completely formatted problem(s). A hot plate with an insulated back is considered. The rate of heat loss by natural convection is to be determined.

### Internal Forced Convection

Please see the attached file for the completely formatted problem(s). The flow through a specified water oioe is given. The pressure drop and pumping requirements are to be determined.

### Question about Internal Forced Convection

Steam is condensed by cooling waterflowing inside copper tubes. The average heat transfer coefficient and the number of tubes needed are to be determined. See attached

### Question About Forced Convection Over Hot Stainless Steel Ball

Please see the attached file for the fully formatted problem(s). A hot stainless steel ball is cooled by forced air. The average convection heat transfer coefficient and the cooling time are to be determined.

### The answer to Forced Convection: Flow over Flat Plates

Please see the attached file for the fully formatted problem(s). The top surface of the passenger car of a train in motionis absorbing solar radiation. The equilibrium temperature of the top surface is to be determined.

### Important information about Forced Convection: Flow over Flat Plates

Please see the attached file for the fully formatted problem(s). Wind is blowing parallel to the wall of a house. The rate of heat loss is to be determined.

### Question about Forced Convection: Flow over Flat Plates

Hot engine oil flows over a flat plate. The total drag force and rate of heat transfer per unit width of the plate are to be determined. See attached

### Heat transfer -- a plane wall -- find maximum temperature in wall

A plane wall of thickness 0.1 m and thermal conductivity of 25 W/mL. The volumetric heat generation of the wall = 0.3 MW/m^3. The wall is well insulated on one side while the other side is exposed to a fluid at 92 degrees Celsius with a convection heat transfer coefficient of h=500 W/m^2. What is the maximum temperature in the w

### Heat Transfer: a Plane Wall; Find Maximum Temperature in Wall

A plane wall of thickness 0.1 m and thermal conductivity of 25 W/mL. The volumetric heat generation of the wall = 0.3 MW/m^3. The wall is well insulated on one side while the other side is exposed to a fluid at 92 degrees Celsius with a convection heat transfer coefficient of h=500 W/m^2. What is the maximum temperature in the w

### Heat Transport: Thermal Circuit Of Brick And Plaster

In this problem we required interior temperatures of a circuit combining brick and plaster, also calculate the thickness of plaster for reducing the heat loss.

### In the convection- diffusion- reaction model

The impulse response function for the concentration of a labelled glycerol in a dog following an injection of m0 grams is given very closely by: C=0, t<0.25 min C=A*t^-1.2, t>=0.25 min Find an expression for the rate of appearance of glycerol, Ra, in the dog.