This study investigates analytically the evaporation heat transfer coefficient of refrigerant R-134a flowing in a heat plate exchanger. With the introduction of new HFC refrigerants, these studies are crucial in designing more efficient refrigeration and air conditioning applications.
This book discusses conventional as well as unconventional wood drying technologies. It covers fundamental thermophysical and energetic aspects and integrates two complex thermodynamic systems, conventional kilns and heat pumps, aimed at improving the energy performance of dryers and the final quality of dried lumber. It discusses advanced components, kiln energy requirements, modeling, and software and emphasizes dryer/heat pump optimum coupling, control, and energy efficiency. Problems are included in most chapters as practical, numerical examples for process and system/components calculation and design. The book presents promising advancements and R&D challenges and future requirements.
This book provides a solid foundation in the principles of heat and mass transfer and shows how to solve problems by applying modern methods. The basic theory is developed systematically, exploring in detail the solution methods to all important problems. The revised second edition incorporates state-of-the-art findings on heat and mass transfer correlations. The book will be useful not only to upper- and graduate-level students, but also to practicing scientists and engineers. Many worked-out examples and numerous exercises with their solutions will facilitate learning and understanding, and an appendix includes data on key properties of important substances.
* Third edition of a well-known and well established text both in industry and for teaching * Fully up-to-date and includes extra problems This book is an aid to heat exchanger design written primarily for design and development engineers in the chemical process, power generation, and refrigeration industries. It provides a comprehensive reference on two-phase flows, boiling, and condensation. The text covers all the latest advances like flows over tube bundles and two-phase heat transfer regarding refrigerants and petrochemicals. Another feature of this third edition is many new problems at chapter ends to enhance its use as a teaching text for graduate and post-graduate courses on two-phase flow and heat transfer. - ;This book is written for practising engineers as a comprehensive reference on two-phase flows, boiling, and condensation. It deals with methods for estimating two-phase flow pressure drops and heat transfer rates. It is a well-known reference book in its third edition and is also used as a text for advanced university courses. Both authors write from practical experience as both are professional engineers. -
This project studied the pool boiling of R-134a and R-123 on smooth and enhanced tubes. This is the 1st phase of ASHRAE project RP-1316 "Experimental Evaluation of The Heat Transfer Impacts of Tube Pitch in a Highly Enhanced Surface Tube Bundle". A Turbo BII-HP and a Turbo BII-LP enhanced tubes were used in this study. These tubes were manufactured and donated by Wolverine Tube, Inc. Four different boiling cases were tested, R-134a on smooth tube, R-123 on smooth tube, R-134a on Turbo BII-HP tube, and R-123 on Turbo BII-LP tube. The first step in this study was performing a modified Wilson plot analysis, once completed, the average and local refrigerant heat transfer coefficients were determined. This thesis also presents the enthalpy-based heat transfer analysis (EBHT), a new method for determining the heat exchanger's overall heat transfer coefficient as a function of the enthalpy change of incompressible fluids. The test tubes' outer diameter is 19.05 mm and length is 1 m. Tests were conducted in a single tube test section, in which the test tube was water heated. All tests were conducted at a saturation temperature of 4.44 °C. The heat flux range is 9.2-126.6 kW/m[superscript]2 for testing with R-134a on smooth tube, 9.2-58 kW/m[superscript]2 for R-123 on smooth tube, 4.1-135.1 kW/m[superscript]2 for R-134a on Turbo BII-HP tube and 4.7-59.8 kW/m[superscript]2 for R-123 on Turbo BII-LP tube. Results show that the heat transfer coefficient increases with heat flux for all cases except the case of R-134a on Turbo BII-HP tube, where it experiences a trend change. Part of this study was comparing the smooth and enhanced tubes performances. R-134a Turbo BII-HP tube to smooth tube heat transfer coefficient ratio changes from 4 at low heat flux to 1.7 at high heat flux. R-123 Turbo BII-LP tube to smooth tube heat transfer coefficient ratio changes from 24 at low heat flux to 7 at high heat flux. The performance of Turbo BII-HP and Turbo BII-LP was found to be very similar over the tested heat flux range of the Turbo BII-LP tube. Comparison plots with available literature are presented.
