Setting Up a Useful Gas Cooler Equation and its Performance Tests

Abstract

The purpose of this paper is to determine an equation enabling the calculation of the temperature at the exit of a gas cooler, knowing the input temperature, the flow rate, the pressure, the gas composition, the temperature of the heat transfer fluid as well as the heat transfer coefficient of the gas cooler and its transfer surface with the constrain to be easily applied and to give acceptable results. This research has been initiated by compressor engineers and experts in charge of checking the compressor installations. This paper consists of 3 parts. • Determining the equation: This section sets out the equations of continuity, momentum and energy applied to a gas particle flowing within a pipe, by using some assumptions. The most important assumption allows us to consider the gas particle as a very thin disk with the same diameter as the “equivalent tube” of the gas cooler and of which the normal is parallel to the axis of the tube. This gas particle therefore has two faces perpendicular to the gas flow. At the end of the demonstration, the gas cooler could be described in a equation where the inputs are the temperature of the gas entering the gas cooler, the outside temperature of the system considered to be that of the heat transfer fluid of the gas cooler, the total transfer surface of the gas cooler, the average molar heat capacity at constant pressure of the gas, the molar mass of the gas, the mass flow rate, the heat transfer coefficient of the gas cooler; and at the end, a fouling factor is introduced to achieve the purpose of this paper. • Numerical application: In this section, the global heat transfer coefficient of a gas cooler is determined. Knowing this value, The error between temperature T2 established by the provider of the equipment at the exit of the gas cooler and temperature T2calc calculated according to the proposed formula in this paper is determined. The error margin is systematically less than ±0.5 °C. • Field tests: Field tests using this method showed: - the tested gas cooler does not meet the specified requirements, - the accuracy of the method applied in field tests is 98%, - the method is very easy to apply on site and gives acceptable results.