The Design And Research Of Adsorption Heat Pump System To Generate Steam

Adsorption heat pump system to generate steam using low-grade waste water and waste gas has the significance of energy conservation and emissions reduction. In this thesis, an open adsorption heat pump system with direct contact heat exchange method for steam generation has been constructed. The reactor is self-designed to optimize the steam generation performance. Hot water（≤85℃） and hot air are substituted for industrial waste water and waste gas to generate high temperature steam directly. Cyclic durability of the system with 13 X zeolite-water is experimentally investigated. Sensitive analyses are also performed in a series of experiments with different operation conditions to study the influence on transient steam generation process. The industrial application prospect is lastly discussed.A large amount of low-grade waste heat from industrial processes is directly discharged to environment. Energy saving technology is in a urgent need to be developed. 13 X zeolite-water working pair was used, and 320 g zeolite was filled in the reactor. Cyclic durability of an open adsorption heat pump system to generate high temperature steam by using low-grade hot water and gas was experimentally tested. According to conditions that can be controlled by the experimental device, the influence factors are discussed through the experiments, for example, initial zeolite temperature, diameter of zeolite particles, temperature and velocity of water flow, temperature and humidity of dry gas and regeneration time. The experimental results and conclusions are shown as follow:（1） Superheated steam at 191℃ ²64 ℃ was generated from the proposed system with input water at 80℃ and dry air at 130℃.（2） Mass ratio of team to the input water is 14.5%, and steam generation rate is 4.87×10-5 kg-s·kg-z-1·s-1 in the cyclic operation.（3） The results of the 15 cycles show that the highest steam temperature at 264℃ and temperature lift at 156℃is generated in the first cycle due to the lowest initial water content in zeolite and highest intergral adsorption heat, whose COP_h（coefficient of performance for heating） and COP_ex（exergy efficiency） are 0.43 and 0.54, respectively. Subsequent 14 cycles’ performance is steady with the gross temperature lift at 94±3℃, COP_h at 0.31⁰.33 and COP_ex at 0.35⁰.37. Thus it can be concluded that the nano-scale pore inside zeolite particle for adsorption keeps almost undamaged under high temperature and high humidity conditions. Water adsorption ability of zeolite remains stable in cyclic operations, which keeps the performance at a considerable level.（4） The performance of two kind of zeolite particles with different diameter but the same material are discussed in this thesis, which shows the performance of 2.22 mm spherical particles is better than 3.88 spherical particles in the system. The outlet steam temperature and moisture of 2.22 mm zeolite reaches equilibrium in atmosphere, so that the outlet steam temperature keeps steady for several minutes.（5） The highest steam temperature can be improved with higher water flow temperature, higher zeolite temperature, higher gas temperature, lower gas humidity by using dryer and more regeneration time. Steam mass can be significantly increased by using higher water feed temperature, higher zeolite temperature, higher gas temperature and lower gas humidity, so as to increase steam generation rate in per cycle. Appropriately increasing the water feed velocity and reducing dry gas feed time can also increase steam generation rate in cyclic operations. COP_h and COP_ex can be improved with higher water feed temperature and lower humidity of dry gas.