关键词: enthalpy of formation;calorimetric determination;natural gas hydrate

Abstract: This paper reports the measurements of enthalpies of natural gas hydrates in typical
natural gas mixturecontaining methane, ethane, propane and iso-butane at pressure in the
vicinity of 2000 kPa (300 psi) and 6900 kPa(1000psi). The measurements were made in a
multi-cell differential scanning calorimeter using modified highpressure cells. The
enthalpy of water and the enthalpy of dissociation of the gas hydrate were determined
fromthe calorimeter response during slow temperature scanning at constant pressure. The
amount of gas released fromthe dissociation of hydrate was determined from the pumped
volume of the high pressure pump. The occupationratio (mole ratio) of the water to gas and
the enthalpy of hydrate formation are subject to uncertainty of 1.5%.The results show that
the enthalpy of hydrate formation and the occupation ratio are essentially independent of
pressure.

Key words: enthalpy of formation, calorimetric determination, natural gas hydrate