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Author

A. Wolf

Bio: A. Wolf is an academic researcher from Imperial College London. The author has contributed to research in topics: Two-phase flow & Air conditioning. The author has an hindex of 2, co-authored 2 publications receiving 109 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a 10.8 m long tube of 31.8 mm internal diameter was used for upward annular flow experiments and the results showed that rapid changes in the film flow parameters occur within 50 tube diameters or so from the inlet.

100 citations

Journal ArticleDOI
TL;DR: In this paper, a model to determine the film Reynolds number has been developed, and is used to show that the onset of disturbance waves and of ephemeral waves happens at a substrate Reynolds number of about 500.

27 citations

Journal ArticleDOI
TL;DR: In this article , the authors report an experimental study performed with refrigeration systems developed using one of natural refrigerants, R-290 (Propane & GWP = 3), particularly with the limited charge amount to meet the most stringent regulatory requirement, IATA - Dangerous Goods Regulation.
Abstract: Recently, natural refrigerants have gained a significant attention as a future alternative because of their performance and environmentally friendly characteristics; No Ozone Depleting Potential and near zero Global Warming Potential. The present paper reports an experimental study performed with refrigeration systems developed using one of natural refrigerants, R-290 (Propane & GWP = 3), particularly with the limited charge amount to meet the most stringent regulatory requirement, IATA - Dangerous Goods Regulation. Under IATA regulation, refrigerating machines and components containing flammable gas are forbidden for international air freight unless the flammable charge shall be less than 100 g. Two types of standalone system were developed, so called Liquid Circulating Chiller and Air-Air Cooler. Both were with air-cooled condensers. Liquid Circulating Chiller consisted of a liquid cooled evaporator (liquid to liquid heat exchanger) while Air-Air Cooler came with an air-cooled evaporator (air to liquid heat exchanger). All component selections were made to achieve the minimum refrigerant charge and as a result, the total system charge was kept around 100 g or less. During the system development, several combinations of the components were considered (e.g., compressors and heat exchangers), and system developed was tested under various test conditions as a part of the system optimization. From the study, the maximum cooling capacity achieved was around 3 kW with less than 100 g of R-290 refrigerant charge.

3 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors used planar laser-induced fluorescence to provide direct visualization of the liquid film in upward vertical air-water annular flow and found that the average film thickness was an increasing function of liquid flow and a decreasing function of gas flow, with the standard deviation approaching 0.4 times the average at sufficient liquid flow.

133 citations

Journal ArticleDOI
TL;DR: In this article, the authors considered algebraic turbulence modeling in adiabatic and evaporating annular two-phase flow, focusing in particular on momentum and heat transfer (so-called "convective boiling") through the annular liquid film.

133 citations

Journal ArticleDOI
TL;DR: In this article, an advanced optical laser-based measurement technique, namely Planar Laser-Induced Fluorescence (PLIF), was used for the visualization of the annular flow over a range of liquid Reynolds numbers and gas Reynolds numbers.

127 citations

Journal ArticleDOI
TL;DR: In this paper, the authors considered the prediction of pressure gradients in adiabatic gas-liquid annular two-phase flow in the macro-to-microscale range.

114 citations

Journal ArticleDOI
TL;DR: In this article, film thickness measurements have been performed in a vertical air/water annular flow in a pipe of 0.05 m diameter and a sensor has been built which allows to measure the film thickness evolution in time at 320 positions.

108 citations