Newsgroups: sci.electronics
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uupsi!rodan.acs.syr.edu!amichiel
From: amichiel@rodan.acs.syr.edu (Allen J Michielsen)
Subject: Re: Re: Microwave Water Heater
Message-ID: <1991May6.211620.6876@rodan.acs.syr.edu>
Organization: Syracuse University, Syracuse, NY
References: <1991Apr28.182011.3357@rodan.acs.syr.edu> <7480018@hpfcso.FC.HP.COM> <1991May6.152846.16704@tc.fluke.COM>
Date: Mon, 6 May 91 21:16:20 GMT

In article <@tc.fluke.COM> strong@tc.fluke.COM (Norm Strong) writes:
>In article @hpfcso.FC.HP.COM> rogerm@hpfcso.FC.HP.COM (Roger Mitchell)
>}restiance heating elements are nearly 100 % efficent in this application

>Yes.  Too bad the process of turning coal into electricity and delivering
>it to your plug is only 25% efficient.  :-(

In Steam by Babcock & Wilcox 38th edition, it is implied that 85-89% is
to be expected.  The materials presented in undergraduate classes suggests
this is optimistic, but a lower working limit of 65% is used.  Then both
Marks and Cooks Reference books use a working number of 80% for Transmission
systems. That would make a working minimum value approaching 50% not 25%.

Then it would only be fair to compare a microwave 'oven' and a antique
resistance heating element in this application.  It shouldn't take a lot
of work to see that the antique is much higher than the microwave.
al



-- 
Al. Michielsen, Mechanical & Aerospace Engineering, Syracuse University
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