Heat balance Definition and 7 Discussions

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species, either cold or hot, to achieve heat transfer. While these mechanisms have distinct characteristics, they often occur simultaneously in the same system.
Heat conduction, also called diffusion, is the direct microscopic exchange of kinetic energy of particles through the boundary between two systems. When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature, at which point they are in thermal equilibrium. Such spontaneous heat transfer always occurs from a region of high temperature to another region of lower temperature, as described in the second law of thermodynamics.
Heat convection occurs when bulk flow of a fluid (gas or liquid) carries heat along with the flow of matter in the fluid. The flow of fluid may be forced by external processes, or sometimes (in gravitational fields) by buoyancy forces caused when thermal energy expands the fluid (for example in a fire plume), thus influencing its own transfer. The latter process is often called "natural convection". All convective processes also move heat partly by diffusion, as well. Another form of convection is forced convection. In this case the fluid is forced to flow by use of a pump, fan or other mechanical means.
Thermal radiation occurs through a vacuum or any transparent medium (solid or fluid or gas). It is the transfer of energy by means of photons in electromagnetic waves governed by the same laws.

View More On Wikipedia.org
  1. U

    Heat conduction from an isotherm spherical cap

    On the surface of a semi-infinite solid, a point heat source releases a power ##q##; apart from this, the surface of the solid is adiabatic. The heat melts the solid so that a molten pool forms and grows. Let's hypothesize that the pool temperature is homogeneously equal to the melting...
  2. B

    Heat transfer for an encapsulated circuit

    Hello, So I am assembling some testing equipment. I have an active circuit, microcontroller, and two battery packs inside a black polypropylene case (which is around 1 ft x 1 ft x 0.5 ft). I was performing a thermal analysis because I want to make sure the electronics do not heat up past around...
  3. G

    Calculation of heat created during compression

    Homework Statement Hello, I have a task to make a heat balance of the evaporator. To do this, I was told to carry a few smaller energy balances in different parts of the evaporator. One of the things I had to calculate was the heat generated during steam compression. -steam is entering...
  4. N

    Temperature ballance, two systems

    Hi, I would like to ask you for advice with a problem, I'm working on. I have a regular shape object (glass cylinder) in which is the 100W heat source. The heat source is ind the middle of cylinder and radiates heat uniformly throughout it’s height. Heat, of course, gradually moving into...
  5. Ravi Singh choudhary

    I In which case coffee will cool faster?

    Just Qualitative Analysis: There are many ways of cooling a coffee cup. But here I want to understand about concept of fins. So I am using a spoon to enhance the heat transfer rate. Put the spoon vertically in the cup. We have two ways to put the spoon, other one is upside down. I am curious to...
  6. T

    Time for a steel die to reach temperature

    Hello. I will be doing some experiments with boron steel. The idea is to heat a steel specimen (200x20x1,5 mm dimensions) to 950°C and then quickly transfer it from the oven to the die at room temperature. When the specimen reaches the steel die it will supposedly be at around 800°C. At this...
  7. N

    Dry ice sublimation, heat balance

    Homework Statement The problem is this: what is the optimum amount of dry ice inside the Styrofoam pack, if we want to received a frozen dough (temp.-18) after 3 days of transportation in temperature 20 C ? My calculations and data placed in the attached excel file, but I'm not sure if they...