Fabrication and Design Aspects of High-Temperature Compact Diffusion Bonded Heat Exchangers
The very high temperature reactor (VHTR), using gas-cooled reactor technology, is one of the six reactor concepts selected by the Generation IV International Forum and is anticipated to be the reactor type for the next generation nuclear plant (NGNP). In this type of reactor with an indirect power cycle system, a high-temperature and high integrity intermediate heat exchanger (IHX) with high effectiveness is required to efficiently transfer the core thermal output to secondary fluid for electricity production, process heat, or hydrogen cogeneration. The current Technology Readiness Level status issued by NGNP to all components associated with the IHX for reactor core outlet temperatures of 750-800℃ is 3 on a scale of 1 to 10 with 10 being the most ready. At present, there is no proven high-temperature IHX concept for VHTRs. Among various potential IHX concepts available, diffusion bonded heat exchangers (henceforth called printed circuit heat exchangers or PCHEs) appear promising for NGNP applications. The design and fabrication of this key component of NGNP is the primary focus of this paper. PCHEs are plate-type compact heat exchangers, in which the plates with the flow passages photochemically etched on them are joined by diffusion bonding. Diffusion bonding is a solid-state joining technique and with carefully controlled bonding variables, this technique offers base metal strength. Alloy 617 is a prime candidate material for high-temperature heat exchangers and other NGNP reactor components. In the current study, two PCHEs, each having 10 hot and 10 cold plates with 12 channels in each plate are fabricated using Alloy 617 plates and will be experimentally investigated for their thermal-hydraulic performance in a high-temperature helium test facility. The high-temperature helium test facility (HTHF), primarily for investigating the heat transfer and pressure drop characteristics of the PCHEs, was designed and constructed at The Ohio State University. The test facility is primarily of Alloy 800H construction and is designed to facilitate experiments at temperatures and pressures up to 800℃ and 3 Mpa, respectively. The PCHE fabrication related processes, I.e., photochemical machining and diffusion bonding are briefly discussed for Alloy 617 plates. Diffusion bonding of Alloy 617 plates with and without a Ni interlayer is discussed. Furthermore, preliminary microstructural and mechanical characterization studies of representative diffusion bonded Alloy 617 specimens are presented. Finally, ASME VIII requirements for the design and fabrication of the diffusion bonded heat exchangers are discussed.
Diffusion bonding Alloy 617 Printed-circuit heat exchanger High-temperature test facility
Sai K. Mylavarapu Xiaodong Sun Richard N. Christensen Richard E. Glosup Raymond R. Unocic
The Ohio State University Columbus, OH, USA Oak Ridge National Laboratory Oak Ridge, TN, USA
国际会议
上海
英文
1648-1664
2010-10-10（万方平台首次上网日期，不代表论文的发表时间）