Heat engineering; a text book of applied thermodynamics for engineers and students in technical schools . a general viewof the work which has been done re-lating to the transmission of heatacross boiler-heating surfaces. Hehas given this view and with it a listof 406 references to various papersdealing with this subject. They arelisted chronologically, by Authors andby Subjects, and the student is re-ferred to this paper for most of the lit-erature on this important subject. The fact that the velocity of thegases affected the rate of transmissionwas experimentally known as early as 1848 but th
Heat engineering; a text book of applied thermodynamics for engineers and students in technical schools . a general viewof the work which has been done re-lating to the transmission of heatacross boiler-heating surfaces. Hehas given this view and with it a listof 406 references to various papersdealing with this subject. They arelisted chronologically, by Authors andby Subjects, and the student is re-ferred to this paper for most of the lit-erature on this important subject. The fact that the velocity of thegases affected the rate of transmissionwas experimentally known as early as 1848 but there does notseem to be a statement of this until 1874 when Prof. OsborneReynolds read a paper before the Literary and PhilosophicalSociety of Manchester (Vol. xiv, 1874, p. 9)1 On the Extentand Action of the Heating Surface for Steam Boilers. In thisvery short paper of a few pages, Reynolds points out the im-portance of the subject. He states that the heat carried offfrom the gas is proportional to the internal diffusion of the fluidat or near the surface, that is, on the rate at which the particles. Fig. 25.—Temperaturegradient. See also The Steam Engine, by John Perry, p. 594. 78 HEAT ENGINEERING which give up their heat diffuse back into the hot gas. This ac-cording to him depends on two things: 1. The natural internal friction. 2. The eddies caused by visible motion which mix up thefluid and continually bring fresh particles into contactwith the surface. The first of these is independent of the velocity, and the secondterm is dependent on the velocity and density of the fluid,the heat transmitted at any point being Q = At + Bmwt (4) where Q = heat per square foot per hourA, B = constants t = difference of temperaturem = density of substance, pounds per cubic footw = velocity along surface in feet per second. He then discusses the quantities A and B and the way in whichthe heating surface may be of more value by an increase invelocity. He finally closes his paper with the
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