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- From: sldf3@pluto.ee.usu.edu (beal weston r)
- Newsgroups: sci.electronics
- Subject: Re: Energy transfer effiency of microwave oven
- Message-ID: <1992Jul27.105105.57516@cc.usu.edu>
- Date: 27 Jul 92 16:51:04 GMT
- References: <1992Jul23.221140.8403@eecs.nwu.edu>
- Organization: Utah State University
- Lines: 38
- Nntp-Posting-Host: pluto.ee.usu.edu
-
- In article <1992Jul23.221140.8403@eecs.nwu.edu>, yeap@eecs.nwu.edu (Kok-Hoo Yeap) writes:
- |> A question about energy transfer in microwave oven:
- |>
- |> A microwave oven with a glass of water, volumn V.
- |> Let Pa be the power draws from the AC outlet,
- |> Pb be the power actually received to heat up the water.
- |> Ef = (Pb / Pa) * 100.0 is the efficiency of energy transfer.
-
- I think that the bottleneck would be the magnetron that converts current to
- microwaves. I have no idea what the efficiency of that is.
-
- |>
- |> If we plot Ef vs V, what does the curve look like ?
- |> Does Ef depends on the volumn of water V, or is it always a constant ?
-
- the energy transfer would depend on the surface area to volume ratio and the
- skin depth of the material. The skin depth is dependant on the resistivity of
- the material and the frequency. Of course the frequency is constant, so the real
- important variables are the resistivity and the surface area.
-
- |>
- |> If Ef depends on what you put in the oven chamber, which
- |> material/food has higher energy transfer efficiency and why ?
-
- salt ( ions ) is quite conductive so the skin depth is shallow. The heat developes
- in the crystals instead of speading throughout.
-
- Anyone feel free to correct me ( be gentle ), but that`s what I remember off hand.
-
-
-
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- %% %%
- %% Weston Beal : I have a piece of hard rock %%
- %% sldf3@sol.ee.usu.edu : candy, but it's not for eating. %%
- %% sldf3@cc.usu.edu : It's for looking through. %%
- %% %%
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