A thermodynamic framework to identify apposite refrigerant former for hydrate-based applications

Abstract

High latent heat storage capacity with naturally assisted salt rejection makes the clathrate compounds appropriate for applications towards load management and desalination processes. Adding to these energy savings are the ease of operations provided by water and the mild conditions at which the refrigerant hydrates are occurred. A direct comparison between these hydrates becomes unfeasible due to the scattered experimental data. Though thermodynamics can streamline this dispersed data, they are currently limited to being a proof of concept most accurately representing the experimental observations. We address this critical deficit of phase assessment and identify, from among R13, R14, R22, R23, R125, R134a and R152a, the most suitable hydrate former for the concerned application. An approach based on van der Waals and Platteeuw model is undertaken and the estimates are quantified in terms of percent average absolute relative deviations (% AARD). An average AARD of 1.75% and 2.68% is observed in pure and aqueous electrolytic phase of NaCl, KCl, CaCl2 and MgCl2, respectively. The model predictions are then estimated at temperature/salinity of 281 K/0 wt% and 284 K/3.5 wt%. Together with the qualitative assessment of the hydrate phase, viz, vapor pressure, compressibility and dissociation enthalpy, R152a refrigerant is observed to be the appropriate former for applications to both load management and desalination.

Proposing Crystallographic Theory to Deparameterize Hydrate Phase Description: Physical Insights and Validation

“…For the sour system, similarly, we compare our approach (% AARD-P = 6.66%) with the models of Sloan and Koh (8.26%), Klauda and Sandler (2.71%), and Chen and Guo (8.06%). As far as refrigerant hydrates are concerned, our formulation deviates by 4.13% compared to the 2.17% error obtained by the approach of Dongre et al, which is a pure system-specific parameter regression-based model. For these three classes of hydrate systems (that consist of eight pure guests, excluding N 2 ), it is observed that despite the nonparametric formulation and great flexibility of the proposed formulation, it leads to secure a fairly good agreement with the experimental data and a competitive performance (even sometimes better) with the widely applied models.…”

“…Here, our approach uses the state correlations of Peyrovedin et al, along with those of Tee et al whenever they are available. For the individual pure guests, Table shows that our formulation secures a competitive performance with the widely used thermodynamic models. ,,,, Further, we categorize the pure guests into three different families, namely alkane (CH 4 , C 2 H 6 , and C 3 H 8 ), sour gas (CO 2 and H 2 S) , and refrigerant (R22, R134a, and R152a), for which, we evaluate our model with accommodating the correlations of Peyrovedin et al in terms of average % AARD-P. For alkane hydrates, our model provides a 3.56% error [5.01% error with the correlations of Tee et al], whereas an error of 5.93% is obtained by the model of Sloan and Koh and 5.31% by that of Chen and Li through data fittings. The ab initio-assisted approach of Klauda and Sandler, with its pure system-specific parameters and large computational load, secures a lowest error of 3.3%.…”

Formulating Noncovalent Interactions for Gas Hydrates with Electrolytes: A New Approach of Stability Analysis

“…In addition to improving our understanding of hydrate stability, the proposed model has practical applications in natural gas extraction and carbon capture and disposal. In transient operations, the model also facilitates the development of hydrate-based desalination technologies. , …”

“…In transient operations, the model also facilitates the development of hydrate-based desalination technologies. 105,106…”