Comprehensive Parameter for Analyzing Condensation in Pneumatic System

The condensation in pneumatic system is a complex physical phenomenon dependant upon status variation and phase transitions,which are related to the parameters of the compressed air,atmospheric conditions and the dimensions of the pneumatic components.Up to now,general research method for this problem is to calculate the status variation and movement quantity by numerical simulation and experiment directly.The comprehensive parameters composed of several different effect factors are rarely used to study the condensation.The composed components and the working conditions of each cylinder are different,a large number of experiments and complex calculations are necessary to determine the condensation.Additionally,the transferability of the determined results is poor.In this paper,the charging and discharging systems of serials cylinder with different structure parameters are studied.The condensation of the systems is observed and the effects of the structure parameters on condensation are analyzed.The changing trends of relative humidity,natural frequency and average speed against the structural parameters of the components during discharge of the pneumatic systems are analyzed.Three comprehensive parameters used to analyze and determine condensation composed by structure parameters of components are proposed,namely,the ratio of the effective area of the discharge tube and the container volume,the square root of the effective area of the discharge tube divided by the product of the container volume and the length of the discharge tube,and the discharge dimensionless tube-volume.The experimental results show that these comprehensive parameters can be used to quantitatively determine whether internal,external or zero condensation occurs in a pneumatic system,and can be also used to quantitatively analyze the experimental data of condensation in pneumatic systems directly.At the same time,the effect factors are too much and the effect relationships are very complex,which causes that the conclusions can＇t be put forward by using single effect factor in experimental data processing individually.The three obtained comprehensive parameters can be used to resolve the above problem.The proposed parameters can also resolve the problem of poor transferability in determining the state of condensation in pneumatic systems,and provide a novel method for the further study of condensation theory.

STUDY ON AUTOMATIC POLISHING AT CONSTANT PRESSURE INTENSITY

Through theoretical and experimental researeh about automatic polishing on thecurved surfaces of the moulds, the limitation of the polishing method at constant pressure, whichis adopted widely in the world, is analysed. Based on the analysis, a new polishing method atconstant pressure intensity is proposed, and the corresponding goveming equation and a com-prehensive polishing parameter are given as well.

Feasibility Analysis of the Operation Strategies for Combined Cooling, Heating and Power Systems (CCHP) based on the Energy-Matching Regime

Although numerous studies have considered the two traditional operation strategies:following the electric load(FEL)and following the thermal load(FTL),for combined cooling,heating,and power(CCHP)systems in different case studies,there are limited theoretical studies on the quantification methods to assess the feasibility of these two strategies in different load demands scenarios.Therefore,instead of a case study,we have undertaken a theoretical analysis of the suitable application scenarios for FEL and FTL strategies based on the energy-matching performance between systems'provision and users'demands.To compare the calculation models of energy saving rate(ESR)for FEL and FTL strategies in the left and right sub-regions of the energy-supply curve,a comprehensive parameter(^)that combines three inherently influential factors(off-design operation parameter,energy-matching parameter,and install capacity coefficient)is defined to determine the optimal installed capacity and feasibility of FEL or FTL strategies quantitatively.The results indicate that greater value of x contribute to a better energy saving performance,and FEL strategy shows better performance than FTL in most load demands scenarios,and the optimal installed capacity occurs when the load demand points were located in different regions of the energy-supply curve.Finally,taking a hotel in Beijing as an example,the value of the optimal install capacity coefficient is 0.845 and the FEL strategy is also suggested,and compared to the maximum install capacity,the average values of the ESR on a typical summer day,transition season,and winter can be enhanced by 3.9%,8.8%,and 1.89%,respectively.