How Much Energy is Needed to Heat LNG from -165°C to 5°C?

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SUMMARY

The total energy required to heat 50 ml of liquid natural gas (LNG) from -165°C to 5°C is approximately 30 kJ, based on calculations using specific heat and heat of vaporization values. The formula Q=MC(T2-T1) is applicable, where H1, H2, and H3 represent different stages of heating and phase change. The specific heat (Cp) was estimated at 2.5 J/kg·K, and the heat of vaporization was approximated at 600 kJ/kg, with a specific gravity of 0.6 for the LNG. These calculations assume worst-case scenarios for safety.

PREREQUISITES
  • Understanding of thermodynamics principles, specifically heat transfer.
  • Familiarity with the formula Q=MC(T2-T1) for calculating heat energy.
  • Knowledge of specific heat capacity and heat of vaporization concepts.
  • Basic understanding of properties of liquid natural gas (LNG) and its behavior at different temperatures.
NEXT STEPS
  • Research the specific heat capacity of LNG and its variations based on composition.
  • Learn about the heat of vaporization for different hydrocarbons, particularly methane.
  • Explore thermodynamic properties of LNG, including density and phase change behavior.
  • Investigate safety factors in energy calculations for cryogenic liquids.
USEFUL FOR

Students studying thermodynamics, engineers working with LNG, and professionals involved in energy calculations for cryogenic processes will benefit from this discussion.

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Homework Statement


I have liquid natural gas, or LNG, at -165degrees Celsius. I want to know the total energy required to heat the gas up 50ml to 5 degrees Celsius.


Homework Equations


Not sure.
Im assuming I need information regarding specific heat etc. Heat of vaporization maybe?

The Attempt at a Solution


Tried to hunt down some more data on LNG but couldn't find it. I do remember a formula from my high school days a long the lines of Q=MC(T2-T1). Not sure however if that only applies to solids?
 
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total energy = H1 + H2 + H3

H1 = (Cp x mass x (bp - (-165oc))
H2 = (heat of vap x mass)
H3 = (Cp x mass x (5oC - bp)

Yes you will need density, specific heat and Heat of vap of the LNG (and b.p of course) - don't know if it will be good enough to use the methane values though
 
Ok I needed a fair amount of safety, so I used worst case scenarios of Cp being 2.5J/kg.K and Vap being approx 600kJ/kg. The specific gravity was 0.6.

I calculated it to being approx. 30kJ. Does that sound correct?
 

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