Convection heat loss

It is advantageous to use a low-retentivity carbon to enable the adsorbate to be stripped out easily. When empirical data are not available, the following heat requirements have to be taken into consideration (1) heat to the adsorbent and vessel, (2) heat of adsorption and specific heat of adsorbate leaving the adsorbent, (3) latent and specific heat of water vapor accompanying the adsorbate, (4) heat in condensed, indirect steam, (5) radiation and convection heat losses. 

Ar higher air speeds > h convective heat loss becomes greater than radiation and approaches Tj. For such conditions Eq. (5.20) is recommended... 

Convective heat loss will depend on the area of skin exposed, the air speed, and the temperature difference between the skin and the... 

Cumulative percent convective heat loss. The effect of high-temperature hydrothermal emissions is included in the 0.1-million-year-old crustal age bin. Data from Wheat, C. G. (2003). Geophysical Research Letters 30, 1895. 

A conservative estimate of the resulting surface temperature is obtained by assuming no convective heat losses from the target structures. Equation 5-23 is used to calculate the surface temperature of the equipment due to an incident radiative heat flux from the fire and accounting for only radiation losses from the target. 

Here we will consider only solid reacting materials, so that we can neglect convective heat losses. With this restriction we only need to equate the self-heating of the system to the algebraic sum of heat loss from the system and heat generation by the system. This is done in... 

Fluidized-bed Coating of an Article A rectangular metal article with dimensions of 0.5 x 5.0 x 10.0 cm is to be coated with PVC powder to a uniform coat thickness of 0.01 cm, using the fluidized-bed coating process. The fluidized-bed temperature is 20°C and the initial metal temperature is 150°C. (a) Assuming no convective losses to the fluidized bed, what would the metal temperature decrease need to be to form the desired coat thickness (b) Estimate the effect of convective heat losses on the temperature decrease of the metal. 

Note that convection heat losses were neglected in the analyses in [18] as radiation is the dominant mode of heat losses at high temperatures. 

The mass transfer coefficient for convective heat loss is proportional to the wind speed. 

Equation (2-18) expresses the critical-radius-of-insulation concept. If the outer radius is less than the value given by this equation, then the heat transfer will be increased by adding more insulation. For outer radii greater than the critical value an increase in insulation thickness will cause a decrease in heat transfer. The central concept is that for sufficiently small values of h the convection heat loss may actually increase with the addition of insulation because of increased surface area. 

An alternative method of integrating the convection heat loss could be used ... 

The convection heat loss from the body is evidenced as a decrease in the internal energy of the body, as shown in Fig. 4-2. Thus... 

A solid body at some initial temperature T is suddenly placed in a room where the air temperature is T and the walls of the room are very large. The heat-transfer coefficient for the convection heat loss is h, and the surface of the solid may be assumed black. Assuming that the temperature in the solid is uniform at any instant, write the differential equation for the variation in temperature with time, considering both radiation and convection. 

Air at 1 atm and 27°C blows across a large concrete surface 15 m wide maintained at 55°C. The flow velocity is 4.5 m/s. Calculate the convection heat loss from the surface. 

A 2.0-cm-diameter horizontal heater is maintained at a surface temperature of 38°C and submerged in water at 27°C. Calculate the free-convection heat loss per unit length of the heater. 

A horizontal pipe l ft (0.3048 m) in diameter is maintained at a temperature of 250oC in a room where the ambient air is at I5°C. Calculate the free-convection heat loss per meter of length. 

Assuming that a human may be approximated by a vertical cylinder 1 ft in diameter and 6 ft tall, estimate the free-convection heat loss for a surface temperature of 75°F in ambient air at 68°F. 

Calculate the free-convection heat loss from a 2-ft-square vertical plate maintained at 100°C and exposed to helium at 20°C and a pressure of 2 atm. 

A 30-cm-diameter horizontal pipe is maintained at a constant temperature of 25°C and placed in room air at 20°C. Calculate the free-convection heat loss from the pipe per unit length. 

Calculate the rate of free-convection heat loss from a 30-cm-diameter sphere maintained at 90°C and exposed to atmospheric air at 20°C. 

A spherical balloon gondola 2.4 m in diameter rises to an altitude where the ambient pressure is 1.4 kPa and the ambient temperature is — 50°C. The outside surface of.the sphere is at approximately 0°C. Estimate the free-convection heat loss from the outside of the sphere. How does this compare with the forced-convection loss from such a sphere with a low free-stream velocity of approximately 30 cm/s ... 

One way to reduce the free-convection heat loss in a horizontal solar collector is to reduce the pressure in the space separating the glass admitting the solar energy and the black absorber below. Assume the bottom surface is at 120°C and the top surface is at 20°C. Calculate the pressures that are necessary to eliminate convection for spacings of 1, 2, 5. and 10 cm. 

Consider a 80-cm long horizontal rod. The right boundary (x = L = 80 cm) is insulated, so that dT/dr = 0, while the left boundary (x = 0) is subject to convection heat loss... 

Dimensionless WSCC Approach In Eq. (5-183), assume the convective heat loss through the refractory is negligible, and linearize the convective heat transfer to the sink. These approximations lead to the result... 

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