Design for Heat Exchanger of Sensible Heat Transfer of Gas Flows for Pebble Bed Reactor Applications

Jesse SchofieldMasters of Engineering in Mechanical EngineeringApril 2010RPI Hartford

Refresher

• Pebble Bed Modular Reactor (PBMR) Application

• Helium-Helium High Temperature Heat Exchanger (HTHX)

• Turbine stream isolation to prevent possible contamination

• Modular design to allow HTHX series with ability to bypass and replacement without losing cooling ability (Achieve transfer with part of the flow).

Methodology

• Evaluation of Equations and relationships

• Apply Researched design limits (fluid properties, expected Reynolds numbers, transfer coefficients, fouling compensation)

• Preliminary Design Creation• Narrowing and Verification of Successful

Design

Revision of Scope

• Previous goal was for a Optimized Design Method

• Revision will be for single or multiple design/s for specific transfers or property ranges

• Reason: Optimized Design Method requires an extensive iteration process to result in a singular best practice exchanger

• Iteration work is a deep research field using novel genetic algorithms or unique computer software

• Project will represent and analytical test case, rather than an encompassing method for any PBMR application

PBMR Application Limits

System Property RangeReactor Outlet Temp 750-900 CReactor Inlet Temp 280-520 C

Reactor Mass Flowrate 120-320 kg/sReactor Helium Pressure 7-9 Mpa

Turbine Inlet Temp 800-890 CTurbine Outlet Temp 480-500 C

Equations and Standards

• IHX System:• LMTD• NTU-e

• Tubeside:• Seider-Tate Eq• VDI-Mean Nusselt Method

• Shellside:• Bell-Delaware Method• Kern Method• Stream Analysis

Method to Design

Assumptions

• Laminar Flow considerations• Helium-Helium• Simple flow network for fouling

considerations• Material Properties for those deemed

within limits (metal alloys, SiC)• Modular design with 5 IHX for full flow

Remaining Work

• Narrowing of Equation Focus• Establishing Clear calculation

walkthrough• Identification of IHX characteristics• Research on certain properties for

conservative assumptions (fouling rate, appropriate design margin, wall thicknesses for design pressures)

Questions?

• Please see personal webpage for updated references