Toru Sawai

Effectiveness of a Balance Chair for Maintaining a Seating Posture During Light-Duty Work

This study discusses the effectiveness of using a balance chair and adjusting a desk height and working position for maintaining seating posture during light-duty work. It is important for a worker to maintain good posture to improve work efficiency and protect his or her health. However, the worker’s body trunk tends to lean forward unconsciously when he or she is working on an ordinary chair. Meanwhile, a person sitting on a balance chair, which comprises a forward-declined seat and a knee pad, can maintain a posture that resembles that of standing. This study measures the body trunk angles of a subject performing light-duty work while seated on an ordinary chair and a balance chair and discusses the influence of desk height and working position.

Analogy between Heat Transfer and Fluid Friction of Gas-Liquid Two-Phase Flow in Minichannel

To investigate the analogy between heat transfer and fluid friction of two-phase flow in minichannel, heat transfer coefficient, pressure drop and void fraction were simultaneously measured for vertical upward heated air-water two-phase flow in a 2.01 mm I.D. stainless steel tube. Void fraction was slightly different from Smith’s correlation and drift flux model, but the latter gave fairly good prediction when α>0.8. Frictional pressure losses were greater than the experimental results of Mishima-Hibiki for a 2.05 mm I.D. Pyrex glass tube and the correlation of Chisholm-Laird. Heat transfer coefficients agreed with our previous experimental results for a 8.03 mm I.D. tube. A theoretical calculation was performed for an annular liquid film flow model using experimental values of wall shear stress and liquid holdup, and satisfactory results were obtained except when the liquid flow rate was very low.Copyright

Estimation of Gas and Liquid Flow Rates in Gas-Liquid Two-Phase System

A new method of estimating gas and liquid flow rates is proposed for a gas-liquid two-phase flow system. The method involves measurement of pressure drops in horizontal and vertical flow channels, and calculation of flow rates by Lockhart-Martinelli correlation. The method does not require the insertion of sensing device into the flow channel and does not rely on previously calibrated correlations. Experiments are performed in slug, froth and annular flow regimes for an air-water system, and the usefulness of the proposed method is examined. The results reveal that gas and liquid flow rates can be estimated with the accuracies of 45% for gas phase and 37% for liquid phase with respect to mean values.© 2002 ASME