Exergy analysis of centered water nozzle steam–water injector

Abstract

A steam–water injector (SI), which is a passive jet pump, has been widely used in various industries. In the present work, exergy analysis models of a centered water nozzle SI were developed based on experiments to evaluate the performance of SI. The thermodynamic perfect degree of SI was found to be not so bad, and exergy efficiency was within the range of 18%–45%. In general, SI is used to work as a pump. However, exergy analysis can only evaluate the thermodynamic perfect degree of SI, but cannot evaluate its lifting–pressure performance. Therefore, thermo–mechanical exergy was divided into temperature–based exergy and pressure–based exergy in the present work, and the pressure–based exergy analysis was introduced. Such analysis was determined to be more reasonable than exergy analysis for a passive jet pump and helpful for achieving optimal SI design. Moreover, the effects of physical and geometric parameters on exergy efficiency and pressure–based exergy efficiency were investigated experimentally, and several optimal values for these geometric parameters were found. Finally, the distributions of exergy losses in separate parts of SI, particularly inevitable exergy losses, were evaluated. These analyses will be helpful in eliminating the effects of inevitable factors and in identifying the key factor, thereby considerably improving SI performance.