Study On Industrial Waste Heat Generation By Organic Rankine Cycle Using Binary Non-azeotropic Mixtures

With the increasing pressure of energy shortage and environmental pollution in ourcountry, the utilisation of low-temperature industrial waste heat by tramsformimg thestored heat into electricity power has become an important mean of energy conservationand emission reduction. Low-temperature industrial waste heat commonly exists in theproduction of building materials, metallurgy, chemical industry and light industry etc.The thermal power conversion efficiency of conventional steam power cycle is limitedby the low temperature of waste heat. This paper uses organic Rankine cycle （ORC） torecycle the industrial waste heat and researches mixtures selection and parameteroptiomization, by which to improve the thermodynamic performance of ORC system.The main research contents are as follows:①To compare the ORC system with binary non-azeotropic mixtures and pureworking fluids, the thermodynamic properties of the systems with pure refrigerantsR245fa, R601a and mixtures R245fa/R601a are analyzed by taking the maximumoutput network as the evaluation. The calculation of system is based on the averagetemperature in two-phase region of mixtures. R245fa/R601a （0.9/0.1） system obtainsthe maximum thermodynamic performance advantage compared to the pure refrigerantssystems. The mixtures system gains better thermodynamic propertie when the massratio of R245fa/R601a is between （0.5/0.5）^0.9/0.1. There is an optimal mass ratiofor optimal thermal performance optimal mass ratio of the system for optimal thermalperformance of the system.②To select the components and the mass ratio of binary non-azeotropicmixtures, seven groups of binary non-azeotropic mixtures are formed. The mixtures areformed with the idea of introducing a component which has inhibition combustioncharacteristics to favorable working fluids which are combustible. These new binarynon-azeotropic mixtures are constituted by R13I1, R227ea, R245fa and DME, R601a,R141b. Sever suitable mass ratio of mixtures are preferred under the evaluation indexesof the thermodynamic properties and the economy of the system. They are respectivelyR245fa/DME （0.8/0.2）, R245fa/R601a （0.4/0.6）, R245fa/R141b （0.7/0.3）, R13I1/R601a（0.8/0.2）, R13I1/R141b （0.6/0.4）, R227ea/R601a （0.7/0.3）, R227ea/R141b （0.8/0.2）.③To select working conditions of the cycle, the preffered mixtures are taken asthe working fluids to compare the output network, exergy efficiency and LEC under different working conditions. The results show that the condensation temperature shouldbe as low as possible under the actual situation; The suitable evaporation temperaturemaintains50℃⁶0℃temperature difference from the waste heat under the conditionof fixed temperature and mass flow of waste heat; The choice of basis calculation pointsfor mixtures infacts the results of working fluids selection. It can improve the systemperformance to choose the basis calculation points reasonably.