Total heat flow

A second property, closely related to the first, is the abiHty of the heat pipe to effect heat-flux transformation. As long as the total heat flow is ia equiHbrium, the fluid streams connecting the evaporatiag and condensing regions essentially are unaffected by the local power densities ia these two... 

Sensible heat flow divided by the total heat flow. 

The overall thermal transmittance, t/, is used to calculate the total heat flow. For a plane surface of area A and a steady temperature difference AT, it is... 

It has been shown that for heat flux rates up to 3.2 kW/m2 the product fdb is constant and that the total heat flow per unit area q is proportional to n. From equation 9.191 it is seen that qb is proportional to n at a given pressure, so that q oc qb. 

This is what we started out to prove, l.e.- AH equals the area of the peak times the total heat flow to the sample. 

The variable gap method is a steady-state method, with the merit that transport of heat by radiation can be separated from the total heat flow ... 

Equation (20) indicates that the total heat flow (Q) is constant over each concentric sphere within the insulating layer. Application of Eq. (20) to the problem described in Figure 5 gives Boundary conditions ... 

The steady-state total heat flow (Q) at r = Rs is determined by using Fourier s law and adding the radiative term ... 

The total heat flow is calculated by inserting Eq. (33) into Eq. (32) ... 

The total heat flow (Q) at the film surface is equal to the mass flow rate (W k) times the heat of condensation (AH). That is, the heat generated by condensation at the surface must be equal to the heat transported away by conduction and radiation for steady state to be achieved. In mathematical terms this results in the equation. 

From the circuit in Figure 11.7, the equivalent conductance, h, allows the total heat flow rate to be represented as... 

Derive an expression for steady-state heat flow through three parallel planes as shown below. In this instance, the total heat flow, Qtot, is a sum of the individual heat flows, Qi. The cross-sectional areas of each plane, A,, are not necessarily equivalent. 

Let us assume that both the reflux rate and the overhead propane product rate are constant. This means that the total heat flow into the tower is constant. Or, the sum of the reboiler duty, plus the feed preheater duty, is constant. If the steam flow to the feed preheater is increased, then it follows that the reboiler duty will fall. How does this increase in feed preheat affect the flow of vapor through the trays and the fractionation efficiency of the trays ... 

The task of the calorimeter is to determine the total heat-flow rate, qtot (the units being W), during a chemical reaction. Generally, any kind of chemical or physical process in which heat is released or absorbed is included. Therefore, qtot can be expressed by Equation 8.3 ... 

Direct evaluation of the convective heat transfer coefficient (h ) of subjects clothed in undergarments and socks (normal ventilated environment) was achieved by observing the sublimation rate of naphthalene balls uniformly positioned three centimeters from the body surface. Equations were developed for prediction of h as a function of metabolic activity and posture, calculation o average skin temperature, and estimation of maximum evaporative heat losses from the body (U2 ). In another approach, the coefficients of dry heat transfer at varying wind speeds for nude and clothed sectional mannequins were determined (U3). At air flow rates above 2 m/sec, percentage contributions of individual body sections to total heat transfer remain constant for the nude and clothed mannequin, yet increased for normally uncovered units such as the face and hands. Generally, the ratio of total heat flow for the nude to clothed mannequin increased with air flow. 

One side of a copper block 5 cm thick is maintained at 260°C. The other side is covered with a layer of fiber glass 2.5 cm thick. The outside of the fiber glass is maintained at 38°C, and the total heat flow through the copper-fiber-glass combination is 44 kW. What is the area of the slab ... 

These heat-flow quantites are directed either in the jc direction or in the y direction. The total heat flow at any point in the material is the resultant of the qx and qy at that point. Thus the total heat-flow vector is directed so that it is perpendicular to the lines of constant temperature in the material, as shown in Fig. 3-1. So if the temperature distribution in the material is known, we may easily establish the heat flow. 

This heat flow will be the same through each section within this heat-flow lane, and the total heat flow will be the sum of the heat flows through all the lanes. If the sketch is drawn so that Ajc = Ay, the heat flow is proportional to the AT across the element and, since this heat flow is constant, the AT across each element must be the same within the same heat-flow lane. Thus the AT across an element is given by... 

Here, Jq is the total heat flow, J, the mass flow of component i, and Jrj the reaction rate (flow) of reaction j. For chemical reactions, linear phenomenological equations are... 

For a system containing a single component, the total heat flow Jq and the reduced heat flow Jq are... 

Conventional DSC measures a sample s total heat flow. This total heat flow is comprised of a heat capacity component and a kinetic component [Eq. (5)]... 

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