EFFECT OF PARTICLE CONCENTRATION AND REYNOLDS NUMBER ON HEAT TRANSFER IN PARTICLE-LADEN FLOWS

Open Access
Author:
Masters, Sarah Renee
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
June 05, 2018
Committee Members:
  • Michael P Manahan Jr., Thesis Advisor
  • Mary I Frecker, Committee Member
  • Stephen P Lynch, Committee Member
Keywords:
  • Particle-laden flow
  • particle concentration
  • solids loading
  • Nusselt number
  • heat transfer
Abstract:
The goal of this research is to understand heat transfer in particle-laden flows. Particle-laden flows are prevalent in multiple industries, including chemical, pharmaceutical, plastics, food, and agriculture. In many applications, it is necessary to heat or cool the particle-laden flow to achieve desired process conditions. It is therefore important to understand the heat transfer characteristics of particle-laden flows under varying process conditions. This research seeks to experimentally investigate how the concentration of particles in turbulent, particle-laden flow effect the heat transfer properties of the flow. An experimental setup to observe the heat transfer properties of particle-laden flows was designed and built in house. A MARK XV-HP powder feeder system was used to entrain copper particles (-325 mesh) into a flow of nitrogen gas. The particle-laden flow then traveled through a horizontal pipe with a constant heat flux applied to the wall. Surface and fluid temperatures along the test section were measured and used to calculate the heat transfer coefficient and Nusselt number of the flow. A range of Reynolds numbers from 30,000 to 65,000 as well as a range of solids loadings from 0.0 to 1.0 were tested. For solids loadings of 0.5, the Nusselt number increased at lower Reynolds numbers and then decreased at higher Reynolds numbers. For solids loadings of 1.0, the Nusselt number was lower at low Reynolds numbers and then increased at higher Reynolds numbers. A transition in Nusselt number occurred for both solids loadings, but they occurred at different Reynolds numbers. The Nusselt number for particle-laden flows did show a variance from the Nusselt number for gas only flows. The direction and quantity of this difference was dependent on solids loading and Reynolds number. These trends are proposed to be a result of different turbulence modulation effects, which are discussed herein.