St. Louis, Missouri
June 18, 2000
June 18, 2000
June 21, 2000
5.382.1 - 5.382.9
Integration of Boiling Experiments in the Undergraduate Heat Transfer Laboratory
Hosni I. Abu-Mulaweh, Josué Njock Libii Engineering Department Indiana University-Purdue University at Fort Wayne Fort Wayne, IN 46835, USA
This paper presents three boiling experiments that can be integrated in the undergraduate heat transfer laboratory. The objective of these experiments is to enhance the understanding of boiling process by undergraduate mechanical engineering students. These experiments expose the students to several important concepts in boiling, such as subcooled boiling, modes of pool boiling, and Leidenfrost Phenomenon. The experimental setup and apparatus required to carry out these experiments is simple. It includes a metallic plate such as brass, stainless steel or aluminum, a heating source such as a Hot Plate, thermocouples, a stopwatch, a liquid dropper, and a camera. These equipments are inexpensive and available in almost all undergraduate heat transfer laboratories.
Boiling and condensing processes play an important role in a large number of practical engineering applications, such as the production of electrical power from vapor cycles, production of refrigeration, and the design of petrochemical processes (such as the refining of petroleum and the manufacture of chemicals). Boiling and condensing are vapor-liquid phase change processes where fluid motion is involved. Due to this fact, boiling and condensing are classified as convective mechanisms. However, there are major differences between these mechanisms and single phase convective heat transfer. This is because there are significant differences between the various fluid properties in the two phases, such as conductivity, specific heat, and density. Also, there is a consumption or release of latent heat hfg which influences the heat transfer rates greatly during phase change.
Both boiling and evaporation are liquid-to-vapor phase change processes, but there are major differences between the two. Evaporation process occurs at the liquid-vapor interface when the vapor pressure pv is less than the saturation pressure psat of the liquid at a given temperature. And evaporation does not involve bubble formation or bubble motion. Examples of evaporation are the evaporation of sweat to cool the human body and the drying of fruits and cloths. On the other hand, boiling occurs at the solid-liquid interface when the temperature of the surface is maintained at a temperature Ts that exceeds the saturation temperature Tsat corresponding to the pressure of the liquid that is in contact with the surface. The boiling process is characterized by
Njock-Libii, J., & Abu-Mulaweh, H. (2000, June), Integration Of The Boiling Experiments In The Undergraduate Heat Transfer Laboratory Paper presented at 2000 Annual Conference, St. Louis, Missouri. https://peer.asee.org/8483
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