			Home About us Contact

Pipe Length (pipe + length)

Distribution by Scientific Domains

Engineering	75%

Selected Abstracts

Flashing characteristics in a pipe downstream from a depressurizing tank and temperature fluctuation characteristics at a mixing tee junction with cold water injection

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2003
Koji Shiina
Abstract The flashing characteristics in a pipe downstream from a depressurizing tank were experimentally and analytically investigated on the basis of the transient test and two-phase flow analysis. The following conclusions were obtained. (1) When the pressure margin of the pump inlet side and the distance to obtain an isothermal condition were sufficient, flashing phenomena did not occur in spite of the decreasing pressure. (2) When the ratio of the cold water injection flow rate to the hot water flow rate Mc/Mh increased, the peak distance of the water temperature fluctuation moved from L/D = 1 to 0, and the maximum water temperature fluctuation ratio was about 40% of the temperature difference between hot and cold water near the mixing tee junction. Because no problem occurred regarding the pipe material thermal fatigue, reliability of the mixing tee junction was assured. (3) Due to suppression of flashing phenomena of the mixing pipe system, the decision diagram on the flashing occurrence was obtained from the test and the analytical results, taking into consideration three factors: the depressurizing ratio in the tank; the cold water injection flow rate due to remaining subcooling; and the delay time of thermal mixing. The simplified analytical equation was used to decrease the cold water injection flow rate by the optimized pipe length between the mixing tee junction and the drain pump. The cold water injection flow rate was minimized when the pipe length was about 15 to 20 times the pipe inner diameter. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 411,429, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10096 [source]

Parametric studies for heating performance of an earth to air heat exchanger coupled with a greenhouse

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2005
M. K. Ghosal
Abstract A thermal model has been developed to investigate the potential of using the stored thermal energy of the ground for greenhouse heating with the help of an earth to air heat exchanger (EAHE) system integrated with the greenhouse located in the premises of IIT, Delhi, India. Experiments were conducted extensively during the winter period from November 2002 to March 2003, but the model developed was validated against the clear and sunny days. Parametric studies performed for EAHE coupled with the greenhouse illustrate the effects of buried pipe length, pipe diameter, mass flow rate of air, depth of ground and soil types on greenhouse air temperatures. Temperatures of greenhouse air with the experimental parameters of EAHE were found to be on an average 7,8°C more in the winter than the same greenhouse without EAHE. Greenhouse air temperatures increase in the winter with increasing pipe length, decreasing pipe diameter, decreasing mass flow rate of flowing air inside buried pipe and increasing depth of ground up to 4 m. Predicted and measured values of greenhouse air temperature, which were verified in terms of root mean square of percent deviation and correlation coefficient, exhibited fair agreement. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Study on Evaporating Characteristics of a Coaxial Two Impinging-Stream Concentrator

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2006
J. Yan
Abstract Based on the coaxial two impinging-streams principle, a new device for solution concentration was built and studied theoretically and experimentally. The experimental study focused on the effects of inlet air temperature, inlet air flow rate, and accelerating pipe length on the volumetric evaporative coefficient of the impinging-stream concentrator (ISC). The results show that the ISC has a relatively high volumetric evaporative coefficient, which increases with higher inlet air flow rates and higher inlet air temperature, and the ISC with a shorter accelerating pipe is more efficient. A theoretical model was suggested based on the consideration of mass, heat, and momentum transfers between liquid droplets and hot air. The concentration process of a sucrose solution in the ISC was simulated using the model and the results were compared with the experimental results, which indicated that the suggested model is reliable with a maximum relative error of less than 6.6,%. [source]