Heat and Mass Transfer

Abstract

In this revised edition of our book we retained its concept: The main emphasis is placed on the fundamental principles of heat and mass transfer and their application to practical problems of process modelling and the apparatus design.Like the first edition, the second edition contains five chapters and several appendices, particularly a compilation of thermophysical property data needed for the solution of problems. Changes are made in those chapters presenting heat and mass transfer correlations based on theoretical results or experimental findings. They were adapted to the most recent state of our knowledge. Some of the worked examples, which should help to deepen the comprehension of the text, were revised or updated as well. The compilation of the thermophysical property data was revised and adapted to the present knowledge.Solving problems is essential for a sound understanding and for relating principles to real engineering situations. Numerical answers and hints to the solution of problems are given in the final appendix.The new edition also enabled us to correct printing errors and mistakes.In preparing the new edition we were assisted by Jens Körber, who helped us to submit a printable version of the manuscript to the publisher. We owe him sincere thanks.We also appreciate the efforts of friends and colleagues who provided their good advice with constructive suggestions.

Comparison of heat transfer in straight and corrugated minichannels with two-phase flow

“…For the straight tube a further heat transfer rate increase is evident. This could be caused via waves which could occur in the condensate film at some section part [1]. At section 2 and 1 only a further cooling down of the condensate is present for the corrugated tube.…”

“…Some small (up to 10%) fluctuations could be observed at condensate flow rates and temperatures for specific flow regimes. 1 For most measurements, the fluctuations were negligible. The condensate was captured during the measurement to the vessel, which was later weighted and divided by the time measured by a stopwatch so an accurate average mass flow rate was obtained.…”

“…The condensate flow rate was set to values corresponding to the rotameter reading of 35, 50, 75, 100, 125 and 150 mm, if the steam pressure was sufficient to provide such flow rate 2 For all combinations of pressure and condensate values, the cooling water flow rate was set to values corresponding to rotameter scale readings from 35 to 55 mm with a 5 mm step, from 60 to 120 mm with a 10 mm step and then the values of 135 and 1 The fluctuations emerged like pulsations especially at low overpressures, about 2 bar and flow rates which were at 75 and 100 mm at condensate rotameter scale values and the lowest cooling water flow rates which ensure an outlet temperature below the boiling temperature. 2 As an example, the maximum flow rate scale value on the rotameter, provided by the absolute pressure of 2 bar, was 100 mm, for a pressure of 3 bar was the scale value 125 mm.…”

Numerical treatment of the temperature distribution in end-pumped composite laser rods

“…The finite difference technique and its explicit scheme were used for the discretization of the mathematical model [27,28]. Here we will only briefly describe discretization of the studied crystal block shown in Fig.…”

Towards development of a prototype high-temperature latent heat storage unit as an element of a RES-based energy system (part 2)

“…Therefore, the heat transfer coefficients α Z and α R in (8), (9) were determined from Hausen correlation corrected for the annular shape of the flow channel [22]. Their typical value was about 2300 W/m 2 K. The values of overall coefficients k HZ and k HR were practically the same as α Z and α R, while the value of k PR was considerably larger: 11800 W/m 2 K. PCM specific heat in the model is temperature dependent.…”