著者

宮田 一司 森 英夫 谷口 隆寛 梅沢 修一 杉田 勝彦

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.855, pp.17-00280-17-00280, 2017 (Released:2017-11-25)

参考文献数

15

被引用文献数

2

---

For the development of industrial heat pump systems supplying high-temperature heat source over 130 °C, experiments were carried out on cooling heat transfer of supercritical pressure HFO1234ze(E) flowing in a plate-type heat exchanger (PHE). HFO1234ze(E) with low Global Warming Potential (GWP) is expected as an alternative to refrigerant HFC134a. In the experiment, heat transfer coefficient data were obtained at different pressures including a near-critical pressure condition. To obtain the heat transfer coefficient, an integral method was used for evaluating the mean temperature difference between the refrigerant and cooling water in the PHE. Based on the measurements, characteristics of cooling heat transfer of supercritical pressure HFO1234ze(E) in the PHE were clarified. Generally, heat transfer coefficient showed considerably large values compared with tube flow, attributed to strong turbulence or agitation promoted by corrugated geometry of the PHE plate, and reached a maximum in the vicinity of the pseudocritical point. As the pressure approached the critical pressure, the peak of heat transfer coefficient became higher at lower bulk enthalpy, reflecting the pressure dependence of isobaric specific heat of the refrigerant. These results mean, even in the pseudocritical region where strong temperature dependency of physical properties appears, properties change in the flow cross section was small compared to the tube flow, although not negligible. The correlation developed in the previous study overestimated the measured heat transfer coefficient in the pseudocritical region for the pressure of the reduced pressure 1.01 very close to the critical pressure and also in the enthalpy region near to and lower than the pseudocritical point for the pressures of the reduced pressure about 1.1 or higher. For the better prediction, the necessity to consider the small but non-negligible properties change in the flow channel cross section was recognized.

著者

宗意 奎太郎 杉田 勝彦 梅沢 修一 川島 久宜 石間 経章

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.850, pp.17-00054-17-00054, 2017 (Released:2017-06-25)

参考文献数

13

被引用文献数

1

---

Water spray is used for cooling suction air of gas turbine for power augmentation. Cooling efficiency depends on the spraying properties. The aim of this study is to investigate the spray characteristics and the influence of secular change in the spray nozzle. PDA (Phase Doppler Anemometry) measurements are conducted at each cross section in wind tunnel which is scale model of inlet duct. Pin type nozzles and a hole type nozzle are tested. Same type nozzles with different using period are also tested. The nozzles are new one and old one which is used 1750 hours before the spray experiments. The spray properties in high spatial-temporal resolution are provided by the PDA. As a result, the droplet size by a pin type nozzle has no change after 1750 hours. The data rate, velocity and flow rate decrease after 1750 hours due to increase of the passage resistance by filter clogged. Pin type nozzles have asymmetry shape in data rate distribution due to the existence of pin. The SMD distributions by pin type nozzles have flat shape in the measurement region. The SMD distributions gradually increase in the value from the center to outer in hole type nozzle. Droplet size dispersion at each measuring point for all nozzles are also evaluated by the experiment. Dispersion of diameter increase in from the center to outer in a hole type nozzle. Also cooling efficiency and the relations of particle density are evaluated. If the particle density is high, the cooling efficiency become small even if the particles have small diameter and high velocity.

著者

森田 良 稲田 文夫 内山 雄太 梅沢 修一 石橋 雅裕 舩木 達也

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.849, pp.16-00526-16-00526, 2017 (Released:2017-05-25)

参考文献数

15

被引用文献数

3

---

In industrial fields, as the steam is commonly utilized for heat supply, drying process and so on, it is important to be aware of the steam flow rate in the view point of energy management. However, the steam utilized in the factory is usually wet steam condition. Though it is well known that the wetness affects the flowmeter reading, it is difficult to clarify the effects of the wetness in the steam flow quantitatively in actual plants and factories, and thus far, there has been no established method for estimating the error caused by the wetness of steam flow. In this paper, the difference of ultrasonic flowmeter reading due to wetness of the wet steam flow was clarified experimentally. Ultrasonic flowmeter reading in the wet steam flow was compared with Coriolis flow meter installed after heat exchanger in the steam apparatus. As a result, we clarified the flow rate difference of those two flowmeters was increased with increasing wetness, and the ultrasonic flowmeter reading was almost the same as the value of steam phase flow rate in the wet steam flow. We also proposed the correction method of the ultrasonic flowmeter reading by using density correction in the flow rate formula of the ultrasonic flowmeter. And finally, we clarified the uncertainty of the measured flowrates and their differences were less than 1.0%.