Joule-Kelvin coefficient

The differential coefficient pi was first investigated by James Joule and William Thomson in the 1850s [23], before Thomson was elevated to the peerage, to become the first Lord Kelvin. So it is also referred to as the Joule-Kelvin coefficient. 

In the treatment of biogas the Joule-Kelvin effect cannot be neglected. A biogas feed contains art equimolar mixture of methane to carbon dioxide. If a pressure of 50 bar is applied at the feed side at 30°C calculate then the recovery S at which the permeate temperature has been decreased below 0°C.(Assume that only carbon dioxide permeates through the membrane and that beat transfer is much faster than mass transfer). The Joule-Kelvin coefficient of carbon dioxide is, = 1.2 K/bar. 

The temperatures T and T can be measured directly. When values of T" versus p" are plotted for a series of Joule-Thomson experiments having the same values of T and p and different values of p", the curve drawn through the points is a curve of constant enthalpy. The slope at any point on this curve is equal to the Joule-Thomson coefficient (or Joule-Kelvin coefficient) defined by... 

In the period 1852-62, J. P. Joule and W. Thomson (later Lord Kelvin) perfected a clever method for measuring the isenthalpic property (dT/dP)Ih which has come to be called the Joule-Thomson coefficient, symbolized /xJT ... 

The coefficient k, expressed in J sec cm is the quantity of heat in joules, transmitted per second through a sample one centimeter in thickness and one square centimeter in area when the temperature difference between the two sides is one degree kelvin (or Celsius). The tabulated values are in microjoules. To convert to microcalories, divide values by 4.184. To convert to mW m divide values by 10. 

FIG. 5-7 Radiation coefficients of heat transfer h,.. To convert British thermal units per hoiir-sqiiare foot-degrees Fahrenheit to joules per square meter-second-kelvins, multiply by 5,6783 = ( F — 32)/l,8,... 

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