How to Calculate Heat Loss During Pipeline Depressurization

The Joule-Thomson effect causes heat loss upon depressurization.
••• Photos.com/Photos.com/Getty Images

When a pressurized gas pipeline is rapidly depressurized (i.e., the gas is allowed to flow rapidly through an open valve to atmosphere), a thermodynamic effect causes the gas to cool. This is called a throttling process or the Joule-Thomson effect. The loss of heat is a function of the expansion of the gas from a high pressure to a lower pressure and is adiabatic in nature (no heat is exchanged).

    Determine the gas that is compressed in the pipeline. For instance, assume that carbon dioxide gas is in a pipeline at a pressure of 294 pounds per square inch (psi) and a temperature of 212 degrees Fahrenheit. At these conditions, the Joule-Thomson coefficient is 0.6375.

    Rearrange the heat loss calculation to isolate the final temperature. The Joule-Thomson equation is μ = (T1 - T2) / (P1 - P2) where μ is the Joule-Thomson coefficient, T1 is the initial temperature, T2 is the final temperature, P1 is the initial pressure and P2 is the final pressure. Rearranging yields -μ x (P1 - P2) + T1 = T2. Assume the final pressure is 50 psi.

    Calculate the final temperature and heat loss in the system. This is done by plugging in the values as -0.6375 x (294 - 50) + 212 = T2 which calculates to be T2 = 56.45. Therefore, the heat loss during depressurization is 212 - 56.45 or approximately 155 degrees Fahrenheit.

    Things You'll Need

    • Pen
    • Paper
    • Calculator

Related Articles

How to Find Partial Pressures
How to Convert Vapor Pressure to Concentration
How to Calculate the Temperature Drop Due to a Pressure...
How to Calculate Volume at STP
How to Calculate Polytropic Efficiency
How to Convert ATM Pressure to Celsius
How to Convert the Volume of Co2 Gas to Liquid
Tutorial of How to Calculate Altitude & Temperature
How to Convert GPM to Cooling Rate in Tons
How to Convert Moles to Pressure
How to Convert Steam Flow to Megawatts
How to Solve for Volume
Experiments With Kinetic Molecular Theory
How to Find the Cross Sectional Area of a Pipe
How to Calculate CFM to MPH
How to Calculate Heat Losses From Storage Tanks
How to Calculate a Temperature Range
What Is the Unit for Enthalpy?
How to Calculate Steam Velocity
How to Convert CV to GPM

Dont Go!

We Have More Great Sciencing Articles!