Direct Contact With The Theoretical And Experimental Study Of The Characteristics Of Gas Hydrate

With the rapid development of the market economy in China, the lack of electric power is now a bottleneck which restricts the development of the national economy. On the one hand, the demand of the electric power increases continuously, on the other hand, the imbalance utility of electric power and the increasing load between peak and off-peak time causes the waste of the electric power resource. Cold storage air conditioning technology uses off-peak power during nighttime to store cold energy and release it as a cold resource for air conditioners during daytime with little use of on-peak electricity. So cold storage air conditioner can shift peaking load efficiently and equilibrate the electric load.Gas hydrate cold storage technology is recognized as a new generation air conditioning technology with bright prospect. It is because that the gas hydrate has comparative latent heat as that of the ice. its phase changing temperature is between 5~13℃, it is compatible with the conventional air conditioner and it has a good chemical stability.First this thesis introduces the background and technology methods of the cold storage air conditioner, then in detail it shows how to build this direct-contact gas hydrate cold storage experimental installation, and the principle of data acquisition and test of the system. This direct contact gas hydrate cold storage installation is composed of a refrigerating system, a viewable hydrate reaction tank, a viewable hydrate storage tank and a cold releasing terminal system. This experimental installation has the characteristics as following:1.It is the first domestic direct contact gas hydrate /binary ice cold storage/release experimental installation with practical value, using a direct contact method improves the heat exchange efficiency, it has got a quicker reaction velocity and a heavy cold storage density.2.The system uses a viewable design. Transparent glasses are installed with the reaction tank, storage tank and the inclined tube with which we can observe the course of the hydrate reaction, storage and heat release directly, also we can take photos and record the processof the hydrate reaction. 3. With a secondary programming to the KINGVIEW configurationsoftware, the testing system has a highly automatic. The installation is compactly designed with practical use.In the 4th chapter, it describes the crystal instruction and the thermodynamic characteristics of the gas hydrate, it also discusses the phase equilibrium of hydrate, the heat and mass transfer of direct contact heat exchange in theory. Chapter 5 gives a detailed analysis including the effect of the sprayer shape and position, the refrigerant flow and different concentration glycol surface additive to the hydrate cold storage process with R11 experiments. The conclusions of the experiments are as following:(1)The opposite two sprayers can get the best heat exchange efficiency generally.(2)An increase refrigerant flow can speed the progress of the hydrate reactions.(3)With the help of the glycol surface active additive, the critical melting temperature of the gas hydrate drops, also the nucleating temperature gets low, the inducement time is shortened, and the nucleating super-cooling degree increases comparing to the condition without glycol. The fluctuation of the temperatures get smoothed during the growing process of hydrate, the hydrate crystal gets fine, also with the help of glycol, the nucleating points can form easily and the hydrate can grow a heavy density.In the last chapter the thesis comes to a conclusion of the experiment of the gas hydrate cold storage, also it shows the prospect of this technology. The author gives his own reasonable advice for the problems existing in the experiment.