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The heat transfer coefficient has SI units in watts per square meter per kelvin (W/(m 2 K)). The overall heat transfer rate for combined modes is usually expressed in terms of an overall conductance or heat transfer coefficient, U. In that case, the heat transfer rate is: ˙ = where (in SI units):
In chemistry, a condenser is laboratory apparatus used to condense vapors – that is, turn them into liquids – by cooling them down. [1] Condensers are routinely used in laboratory operations such as distillation, reflux, and extraction. In distillation, a mixture is heated until the more volatile components boil off, the vapors are ...
A condenser is designed to transfer heat from a working fluid (e.g. water in a steam power plant) to a secondary fluid or the surrounding air. The condenser relies on the efficient heat transfer that occurs during phase changes, in this case during the condensation of a vapor into a liquid. The vapor typically enters the condenser at a ...
Here, is the overall heat transfer coefficient, is the total heat transfer area, and is the minimum heat capacity rate. To better understand where this definition of NTU comes from, consider the following heat transfer energy balance, which is an extension of the energy balance above:
Q is the exchanged heat duty , U is the heat transfer coefficient (watts per kelvin per square meter), A is the exchange area. Note that estimating the heat transfer coefficient may be quite complicated. This holds both for cocurrent flow, where the streams enter from the same end, and for countercurrent flow, where they enter from different ends.
However, the heat transfer coefficient is a function of the temperature difference in natural convective (buoyancy driven) heat transfer. In that case, Newton's law only approximates the result when the temperature difference is relatively small.
Heat flow calorimetry measures the heat flowing across the reactor wall and quantifies this in relation to other energy flows within the reactor. = where: → process heating (or cooling) power (W) → overall heat transfer coefficient (W/(m 2 K))
Liebig condenser. The Liebig condenser (/ ˈ l iː b ɪ ɡ /, LEE-big) [1] or straight condenser is a piece of laboratory equipment, specifically a condenser consisting of a straight glass tube surrounded by a water jacket. In typical laboratory operation, such as distillation, the condenser is clamped to a retort stand in vertical