Study On The Promoting Effect Of Additives On The Rapid Formation Of Hydrate

Air conditioning is gradually used to regulate the indoor environment in life and work.But it brings some problems,such as energy and environment problems.The cold storage technology can be used to alleviate this problem and balances the peak-to-valley difference.Water,ice and eutectic salt are the common medium used to store cold energy.Hydrate is an air-conditioning cold storage medium,which is been studying and developing.The phase transition temperature of hydrate is between 5 and 12℃,which can well fit the conventional air-conditioning system.Hydrate cold storage density is higher,which can better reduce the volume of cold storage equipment.However,the cold storage capacity of hydrate is often related to its formation.It is an important task to find the environmentally friendly accelerators to improve hydrate formation.In this work,natural amino acids and amino acid surfactants are selected as the additives to study the effect of these additives on hydrate formation refrigerant HCFC-141b.The promotion mechanism of hydrate formation is analyzed.The main work is as follows:（1）The effects of natural amino（acids leucine,valine,methionine,tryptophan and phenylalanine）on HCFC-141b hydrate formation are studied.The optimal concentration of different kinds of amino acids is different,but all of them can effectively shorten the induction time of hydrate formation.The amino acid side chain group is the key factor affecting the nucleation and growth of hydrate.The hydrophilic index of amino acid also affects hydrate formation.Aromatic amino acids have more advantages in shortening the induction time of hydrate formation and increasing the growth rate of hydrates,while aliphatic amino acids is conducive to produce large amounts of hydrate.（2）The hydrate formation of HCFC-141b containing amino acid surfactants（sodium cocoyl glutamate and sodium stearoyl glutamate）is investigated.Amino acid surfactants can reduce the surface tension of solution and increase the contact of water with HCFC-141b,which promotes hydrate formation.The hydrates nucleation and growth are studied by using microscopic.The droplets of HCFC-141b improve the nucleation and growth of hydrate.The mechanism of effect of amino acid surfactant on HCFC-141b hydrate formation is explained by the microscopic images.（3）The cold storage capacity of HCFC-141b hydrate is measured by mixed calorimetry method,where the experimental system is the same as that used in Chapter 2 and 3.It is found that the aliphatic group of amino acid is more beneficial to increase the hydrate production and cold storage capacity.Among the three aliphatic amino acids,the cold storage capacity of hydrate also increased with the increase of the hydrophilic index of the amino acid.The average cold storage capacity of hydrate can reach up to 261.24 k J·kg^-1with valine.The hydrate cold storage capacity with either amino acid surfactant is similar.The hydrate cold capacity is about 229.10 k J·kg^-1when 1.0 wt%sodium stearoyl glutamate is added.