Date on Master's Thesis/Doctoral Dissertation

12-2014

Document Type

Master's Thesis

Degree Name

M.S.

Department

Mechanical Engineering

Committee Chair

Brehob, Ellen

Committee Co-Chair (if applicable)

Park, Sam

Committee Member

Berson, Robert E. (Eric)

Subject

Heat--Transmission; Heat pumps

Abstract

In the field of magnetocaloric heat pumps, many system models have been made. What most of these models lack is heat transfer occurring while there is no fluid motion. It is the objective of this paper to analytically determine and experimentally verify heat transfer with no bulk fluid motion. The addition of a pure dwell period to the typical magnetocaloric cycle was shown to have a positive performance impact in specific conditions. These conditions correspond to regenerators that are heat transfer rate limited in operation. The heat transfer mechanism for this particular case was shown to be pure conduction via a CFD study. Toroidal convective currents were present, but flow velocity was miniscule. Assuming pure conduction, an analytical model was created to calculate average heat transfer coefficient from geometric parameters and material properties. This heat transfer coefficient was rolled into an exponential coupled two mass model, which was validated via a time stepping model. In order to experimentally validate the model, two experiments were performed. The first experiment yielded particle sphericity; which allows for an independent measurement of heat transfer area. The second experiment was performed in order to measure fluid temperature over time for various particle diameters, particle thermal conductivities, and fluid conductivities. The coupled two mass exponential model was fitted to the output of these tests to find ��ℎ� (Heat transfer coefficient multiplied by heat transfer area). Heat transfer area was separately determined, allowing heat transfer coefficient � to be separated from area and compared with the analytically determined values.

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