Heat flow rate
Heat flow is the quantification of energy transfer resulting from a temperature disparity, leading to a thermal equilibrium between substances. In this context, this energy is referred to as heat.
The heat flow, measured in Joules per second (J/s), is the amount of heat passing from one substance to another per unit of time. This unit is commonly expressed as Watts (W), which is a standard indicator for power.
Heat transfer processes occur through heat conduction (conduction), heat flow (convection), or heat radiation (radiation).
- Heat conduction pertains to the transport of heat within solid bodies or between bodies in direct contact.
- Heat flow is observed when liquid or gaseous media move through conduits, carrying heat along with them.
- Heat radiation involves the emission of electromagnetic waves in the infrared range.
The transfer of heat from one fluid through a wall to another fluid is termed heat transfer. Each process has its specific formula for calculating heat flow.
In engineering, knowledge of heat flow rates is crucial for calculating heat losses, designing heat exchangers, and determining energy requirements for cooling and heating. The formulas used typically incorporate empirically determined material properties that approximate the actual characteristics of the medium.
These material properties are also temperature-dependent and undergo changes during the considered processes. To obtain accurate results, measuring instruments equipped with heat flow sensors are employed. These sensors leverage thermoelectric effects, detecting electrical variables that undergo defined changes in response to heat flow, allowing for precise assessments.
For a deeper understanding, one can explore the principles of Differential Scanning Calorimetry (DSC) and discern the distinctions between DSC and Dynamic Thermal Analysis (DTA) in our blog. We also delve into the disparities between conduction, convection, and radiation in another blog post.
- Read more about the principle of Differential Scanning Calorimetry and the difference between DSC and Dynamic Thermal Analysis DTA.
- In our blog we describe the difference between conduction, convection and radiation.