Heat Equation
Heat Equation - Related Videos
02:55
Thermochemical Equations
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2020
For a chemical reaction (the system) carried out at constant pressure – with the only work done caused by expansion or contraction – the enthalpy of reaction (also called the heat of reaction, ΔHrxn) is equal to the heat exchanged with the surroundings (qp). The change in enthalpy is an extensive property, and it depends on the amounts of the reactants participating in the reaction (or the number of moles of reactants). The change in enthalpy is specific to the reaction, and the physical...
08:35
Testing the Heat Transfer Efficiency of a Finned-tube Heat Exchanger
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2023
Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA Heat exchangers transfer heat from one fluid to another fluid. Multiple classes of heat exchangers exist to fill different needs. Some of the most common types are shell and tube exchangers and plate exchangers1. Shell and tube heat exchangers use a system of tubes through which fluid flows1. One set of tubes contains the liquid to be cooled or heated, while the second...
02:35
Clausius-Clapeyron Equation
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2020
The equilibrium between a liquid and its vapor depends on the temperature of the system; a rise in temperature causes a corresponding rise in the vapor pressure of its liquid. The Clausius-Clapeyron equation gives the quantitative relation between a substance’s vapor pressure (P) and its temperature (T); it predicts the rate at which vapor pressure increases per unit increase in temperature. where ΔHvap is the enthalpy of vaporization for the liquid, R is the gas constant, and A is a constant...
03:10
Chemical Equations
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2020
Chemical equations represent the identities and relative quantities of substances involved in a chemical reaction. The substances undergoing reaction are called reactants, and their formulas are placed on the left side of the equation. The substances generated by the reaction are called products, and their formulas are placed on the right side of the equation. Plus signs (+) separate individual reactant and product formulas, and an arrow (→) separates the reactant and product (left and right)...
02:59
The Nernst Equation
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2020
Nonstandard Reaction Conditions The interconnection between standard cell potentials and various thermodynamic parameters such as the standard free energy change ΔG° and equilibrium constant K has been previously explored. For example, a redox reaction involving zinc(II) and tin(II) ions at 1 M concentration with Eºcell = +0.291 V and ΔG° = −56.2 kJ is spontaneous. Discharge of this cell, however, results in a change in the reactant concentration and a steady decrease of the cell potential. At...
FAQs
These properties set the material-dependent response of a thermal model. Thermal conductivity, density, and specific heat collectively govern the rate at which temperature changes, so changing the material changes the predicted temperature field even when the geometry and operating conditions remain the same. Engineers therefore include them when comparing materials or evaluating thermal performance.
Boundary conditions specify the thermal behavior imposed at the edges or interfaces of the modeled region. Because the temperature field depends on these conditions, changing them can alter both transient predictions and the eventual steady-state result. Careful specification is therefore essential when using the equation to assess a structure, electronic component, manufacturing system, or energy device.
A transient analysis follows temperature fields as they evolve through time, whereas a steady-state analysis focuses on the established thermal condition after time-dependent changes have been considered. This distinction lets engineers study heating or cooling behavior separately from the final thermal condition, supporting safety assessment and design decisions.
Energy conservation provides the accounting principle for thermal energy, while Fourier’s law describes heat conduction through a material. Combining these foundations connects heat flow with changes in temperature. This physical basis allows the resulting model to represent thermal behavior consistently and supports predictions used in engineering analysis and system design.
An engineering analysis must identify the material properties governing the rate of temperature change, define the relevant boundary conditions, and distinguish whether the goal is a transient or steady-state temperature field. The resulting prediction can then be examined for thermal performance, safety, material selection, or system design.
The equation supports thermal analysis in structures, electronics, manufacturing systems, and energy devices. In these settings, predicted temperature fields help engineers evaluate how designs behave thermally, select suitable materials, manage heat, and assess safety. Its value extends from understanding temperature evolution to guiding practical decisions about component and system design.