Recuperator with microjet technology as a proposal for heat recovery from low-temperature sources

Abstract

A tendency to increase the importance of so-called dispersed generation, based on the local energy sources and the working systems utilizing both the fossil fuels and the renewable energy resources is observed nowadays. Generation of electricity on industrial or domestic scale together with production of heat can be obtained for example through employment of the ORC systems. It is mentioned in the EU directive 2012/27/EU for cogenerative production of heat and electricity. For such systems the crucial points are connected with the heat exchangers, which should be small in size but be able to transfer high heat fluxes. In presented paper the prototype microjet heat exchanger dedicated for heat recovery systems is introduced. Its novel construction is described together with the systematical experimental analysis of heat transfer and flow characteristics. Reported results showed high values of the overall heat transfer coefficient and slight increase in the pressure drop. The results of microjet heat exchanger were compared with the results of commercially available compact plate heat exchanger.

Thermal-Hydraulic Studies on the Shell-and-Tube Heat Exchanger with Minijets

“…Therefore, the crossflow role cannot be neglected in the case of the proposed solution of the heat exchangers. An theoretical and experimental analyses of the prototype constructions [27,28] revealed that the innovative idea of jet technology application facilitates in particular the heat transfer at low fluid flow rates and/or with a small temperature difference between fluids. This paper presents further research conducted on the intensification of heat transfer and reduction of the hydraulic resistance in a patented design of the minijet heat exchanger [24], for a future optimization of the construction.…”

Turbulence models impact on the flow and thermal analyses of jet impingement

“…In Table 3, locations of turbulence kinetic energy maxima are listed, in relation with orifice diameter D. They were established for flat and non-flat cases in the same manner, as data from Figure 8. Differences between each case existit is an important aspect to mention, because it may influence the results when the jets array impingement occurs, such as in [1][2][3]. Multiple jets might strongly interfere with each other.…”

“…It was being used in the cooling systems of electronics or in some metallurgical processes. Recently, however, it was proposed in the novel construction of cylindrical heat exchanger [1], which resulted in very promising values of transferred heat rates and lower than in other similar devices hydraulic resistance [2][3].…”

“…The following paper regards the analysis of single minijet that impinge various surfaces -flat, convex and concave. Their geometry was chosen in the basis of previous research [6], as well as data from [1][2][3]. While the available information for the flat case is generally broad, non-flat impingement is still not a popular and widely described scientific topic.…”

“…While the available information for the flat case is generally broad, non-flat impingement is still not a popular and widely described scientific topic. Correlations do not exist, which can be used in the problems regarded in [1][2][3]. The goal of paper was to identify the turbulence model impact on the results and describe the differences between impingement on various surfaces -since such knowledge would be essential to correctly analyze arrays of minijets, existing for example in heat exchangers [1][2][3].…”