Thermal analysis of integrated hydrate-based desalination system with intermediate fluid type LNG vaporizer

Abstract

With a growing population, excessive industrial activities, and limited freshwater resources, water scarcity is considered a prime global risk. Desalination of seawater is essential to overcome former challenges, however, energy-intensive water desalination processes have pushed the water community towards sustainable and economical seawater desalination techniques. This study presents a hydrate-based desalination (HyDesal) system where liquefied natural gas (LNG) is suggested to be used as a source of cooling energy and hydrate former. The study's novel use of an intermediate fluid type LNG vaporizer (IFV) is a prime objective. Detailed analysis of the complex heat transfer processes of the LNG vaporizer is conducted to estimate the thermal performance of the LNG vaporizer using a model based on the heat transfer analysis of each of the three sub-components of the IFV. The analysis for each sub-component is coupled as a set of linear equations in matrix form. An algorithm was also designed and developed to assess the thermal parameters of the IFV in an iterative procedure. The former algorithm is suggested to evaluate the performance of the complex heat transfer processes of the IFV. Furthermore, the effect of various operating parameters of the LNG vaporizer on its performance is investigated. Besides, a general thermal analysis of the suggested hydrate-based desalination system is investigated. Design parameters of the desalination system, such as the required mass flow rate of the seawater, mass flow rate of the hydrate former, and operating conditions are evaluated. In addition, a statistical thermodynamics model (modified van der Waals and Platteeuw) was also employed to trace the hydrate phase boundary in the presence and absence of inhibitors. The coupled thermodynamic model provides an accurate update of process T or P conditions along with fractional cage occupancies.