Thermodynamic characterization of mixed gas hydrates in the presence of cyclopentane as guest molecule for an application in secondary refrigeration

Abstract

Gas hydrates have drawn the attention of many scientists because of their potential role in energy applications. By using some thermodynamic promoters, it is possible to form hydrates at reduced pressure and near ambient temperature, which are suitable formation conditions for most industries. In this study, a high pressure micro differential scanning calorimeter was used to measure the dissociation conditions of mixed cyclopentane (c-C5H10) + CO2 hydrates in the system composed of liquid water + liquid hydrocarbon + hydrate + vapour, in a pressure range of 0 to 4.3 MPa in a temperature range of 280 to 292 K. The analysis of the heat flow curve allowed the direct determination of the dissociation enthalpy of c-C5H10 + CO2 hydrates (e.g., ΔH=462.5±1.5 kJ. kg−1water at equilibrium pressure 0.25 MPa) and the average mass heat capacity of c-C5H10 + CO2 hydrates in a temperature range of 277.9-281.2 K (CpH = 1479.09 ± 137.43 J. K−1. kg−1hydrate at 0.25 MPa).