| Adsorption energy storage technology has great application potential in terms of solar energy and waste heat utilization.The aim of this study is to develop high efficiency compound adsorbent for improving the utilization of solar energy and waste heat and expanding its utilization.The combination method of theoretical analysis and experimental research is used to improve and develop the comprehensive performance testing equipment and method of adsorbent.In addition,a rapid characterization method for comprehensive performance of trace adsorbents was constructed,and the long-term cycle adsorption performance changes were also studied.Finally,the preparation process of new graphite-carbon film-salt adsorbent was optimized,and the thermal mass transfer and kinetic characteristics of adsorbent equilibrium state were studied and discussed.Meanwhile,the application of adsorbent in solar energy storage is preliminarily expanded.In order to solve the problems of high cost,low test efficiency,accuracy deviation of test samples and poor universality of various performance test devices of adsorbent.The transient heat conduction test device and permeability test device of the volumetric method test system were innovatively improved.In general,testing cost and accuracy have been significantly improved.The developed volume method comprehensive test system can realize the dynamics,equilibrium state,long-term cyclic adsorption characteristics and comprehensive performance testing of 0.5g-3g trace samples.The thickness of heat and mass transfer direction in the reactor is only 2mm,and the designed thermal response time of the armored thermocouple for temperature measurement is less than Is.It can actually reflect the temperature change inside the adsorbent.The overall test accuracy is less than 2.3%,which can meet the low cost and high precision research and development needs of adsorbent.Furthermore,a new type of thermodynamic probe was developed,and the thermodynamic testing probe for small size and large resistance was obtained by means of winding.The testing accuracy was less than 2%.A thermal conductivity testing device was developed for ammonia gas environment,and the thermal conductivity testing of composite adsorbent with different adsorbents was realized by transient method.The overall test error was less than 2%.Temperature control and pressure control devices have been added in the existing permeability test equipment.Based on the balance test data,the permeability of micro samples has been tested with the change of adsorption amount.The test speed is fast,the sample filling volume is small,and the test error is less than 4%.Finally,adsorbent adsorption performance and heat and mass transfer performance of test device were innovatively studied,a set of test samples of low cost,less dosage and high integration of adsorbent performance characterization system was built.In order to solve the lack problem of rapid comprehensive properties quantitative characterization methods of micro adsorbent samples,this study presented the method of rapid characterization of the unit mass power density(SCPv)of the absorbent and the long-term cyclic performance test scheme based on the ideal adsorption cycle process.This result shown that SCPv value was a good represent way of comprehensive performance and the real performance of the adsorbent sample.In view of the low specific surface area of the expanded graphite matrix and the small load of AEMH,a new method for the preparation of a compound adsorbent for the precursor of soluble sugar was proposed,and a graphite carbon membrane salt composite adsorbent was obtained.In the initial stage of adsorption,the best samples were Q2-475-2.5h,and the SCPv value reached 4.37kJ/kg,which was 51.2%and 21.8%higher than that of calcium chloride and graphite/calcium chloride respectively.The long term performance of the sample preparation process is:a)the optimum parameters of the process are the carbon content in sugar and the molar ratio of calcium chloride to 1:1 to 2:1,the burning temperature of 400? and the burning time from 2.5 to 3.5h.b)When the molar ratio of carbon to calcium chloride in sugar is 1.5:1 to 2:1,the firing temperature is 475 degrees and the firing time is 2.5h.The accuracy of preparation parameters of better samples is lower,which is conducive to industrial scale production.The Q3-400-3.5h value of the samples with long term performance was 150 times,and the SCPv value reached 4.31kJ/kg,which was 20.1%higher than that of the graphite calcium chloride sample.After 150 cycles of adsorption,the adsorption rate of the samples with better long-term performance increased obviously,and the cyclic adsorption amount increased or remained flat.The graphite carbon film-AEMH composite adsorbent had good long-term comprehensive performance.From the microscopic structure,the preparation process of graphite carbon film-AEMH composite adsorbent can realize the formation of Nano-scale honeycomb like carbon film structure in the expanded graphite microporous wall,effectively increase the load area,realize the three-dimensional load of calcium chloride in the graphite micro-pores,and the dispersion level is not up to the nanometer level.The initial performance is poor.There is a dense layer on the outer wall of the new prepared sample.After many cycles,it is necessary to expand through calcium chloride to form micro-pores and connect the internal honeycomb like structure to achieve the rapid improvement of adsorption rate and adsorption capacity,and to effectively improve the long-term performance of the adsorbent.In order to reveal the existence mechanism of the pseudo equilibrium region,the adsorption and desorption phenomena in the pseudo equilibrium region are confirmed by adopting the thermal perturbation method.A more rigorous equilibrium model is deduced in theory,and the existence mechanism of pseudo-equilibrium region is explained reasonably.To improve the universality and precision of the equilibrium model,the introduction of the conversion as a third variable,the development of a new equilibrium equation,completed the common pressure condition(0.18?1.5 MPa)and temperature conditions(35?105?)adsorbent equilibrium under temperature and pressure and the conversion of data measurement,through simulation and validation of the new model,the reliability of model prediction and versatility was verified.The heat and mass transfer properties of new graphite-carbon film-salt composite adsorbent were studied.The heat and mass transfer properties of pure expanded graphite showed obvious anisotropy.However,due to the existence of amorphous carbon film,it is difficult to form a regular superimposition sheet thin layer.The anisotropy of the heat and mass transfer process of graphite carbon membrane salt composite adsorbent is not obvious.The adsorption capacity has a very obvious influence on the heat and mass transfer capacity of the adsorbent.With the increase of the adsorption capacity,the maximum thermal conductivity of the adsorbent can be doubled.When the maximum mass transfer capacity can be reduced by an order of magnitude,the influence of this factor must be considered when the adsorption bed is designed.In the preparation factors,the influence of sugar content on heat conduction and permeability is the most,the burning temperature is the second,and the burning time is the least.The essence is that the carbon film formed by sugar carbonization hinders the mass transfer channel,and affects the graphite scale to form an effective heat transfer channel,but the decrease of thermal conductivity is not obvious.After 100 cycles,the carbon film gradually passes through the adsorption and desorption process and forms through holes.The permeability of the Q4-475-2.5h is nearly doubled,and the mass transfer capacity of the sample is similar to that of the graphite calcium chloride sample.In general,the heat and mass transfer capacity of the new composite adsorbent is similar to that of graphite calcium chloride.Considering the actual structure factor of adsorbent,the dynamic model of adsorbent was improved,and the actual prediction error was less than 5%.In order to solve the problem of heat transfer process of solar energy storage and low efficiency of energy storage,an adsorptive energy storage unit coupled with heat storage energy was proposed.The experiment test results shown that the cooling capacity of the energy storage unit is 1185.7kJkg,and the heat storage capacity is about 2419.8kJ/kg,this research can reach the expected effect.In conclusion,a set of perfect adsorbent testing,R&D and evaluation scheme has been formed in this paper.The research and development of graphite-carbon film-salt composite adsorbent with good heat and mass transfer capacity and long-term performance were completed.The theory of adsorption equilibrium was improved and developed,and the study on heat and mass transfer characteristics of composite adsorbent was enriched.In addition,an efficient integrated collector unit for heat storage is proposed,which has good energy storage effect.It is of great significance to the efficient development of adsorbent and the practicability of adsorption energy storage system. |
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