Search results
Results From The WOW.Com Content Network
The exchange current density is the current in the absence of net electrolysis and at zero overpotential. The exchange current can be thought of as a background current to which the net current observed at various overpotentials is normalized. For a redox reaction written as a reduction at the equilibrium potential, electron transfer processes ...
Logarithmic mean temperature difference. In thermal engineering, the logarithmic mean temperature difference ( LMTD) is used to determine the temperature driving force for heat transfer in flow systems, most notably in heat exchangers. The LMTD is a logarithmic average of the temperature difference between the hot and cold feeds at each end of ...
Heat transfer coefficient. In thermodynamics, the heat transfer coefficient or film coefficient, or film effectiveness, is the proportionality constant between the heat flux and the thermodynamic driving force for the flow of heat (i.e., the temperature difference, ΔT ). It is used in calculating the heat transfer, typically by convection or ...
Ground-coupled heat exchanger. A qanat and windcatcher used as an earth duct, for both earth coupling and evaporative cooling. No fan is needed; the suction in the lee of the windtower draws the air up and out. A ground-coupled heat exchanger is an underground heat exchanger that can capture heat from and/or dissipate heat to the ground.
In chemistry and physics, the exchange interaction is a quantum mechanical constraint on the states of indistinguishable particles. While sometimes called an exchange force, or, in the case of fermions, Pauli repulsion, its consequences cannot always be predicted based on classical ideas of force. [1] Both bosons and fermions can experience the ...
Cation-exchange capacity is defined as the amount of positive charge that can be exchanged per mass of soil, usually measured in cmol c /kg. Some texts use the older, equivalent units me/100g or meq/100g. CEC is measured in moles of electric charge, so a cation-exchange capacity of 10 cmol c /kg could hold 10 cmol of Na + cations (with 1 unit ...
The effective exchange rate is an index that describes the strength of a currency relative to a basket of other currencies. Typically it is calculated using geometric weighting. It can be computed using the USD as a numeraire. This means the constituent exchange rates are all first defined vis-a-vis the USD.
Respiratory exchange ratio. The respiratory exchange ratio ( RER) is the ratio between the metabolic production of carbon dioxide (CO 2) and the uptake of oxygen (O 2 ). [1] [2] The ratio is determined by comparing exhaled gases to room air. Measuring this ratio can be used for estimating the respiratory ratio (RR), an indicator of which fuel ...