Helical Screw Expander Research Articles

408 トータルフロースクリューエキスパンダの基本設計に関する一考察(新エネルギー(2))

The purpose of our study is effective energy conversion from geothermal resources. But most of the geothermal resources are liquid dominated. Though the turbomachinery is not suitable for wet steam, helical screw expander is studied to apply the total flow power conversion machine. Theoretical work and efficiency were calculated using already proposed practical formula. If the operating conditions are not equal to the design conditions, the influences are greater at low dryness region. Then, it is necessary to understand the overview of the performance using practical formula before detailed design of total flow screw expander.

219 トータルフロースクリューエキスパンダの理論効率(GS24熱工学)

219 トータルフロースクリューエキスパンダの理論効率(GS24熱工学)

403 トータルフロースクリューエキスパンダの出力特性(応用熱工学I)

403 トータルフロースクリューエキスパンダの出力特性(応用熱工学I)

Energy and exergy analyses on a novel hybrid solar heating, cooling and power generation system for remote areas

In this study, a small scale hybrid solar heating, chilling and power generation system, including parabolic trough solar collector with cavity receiver, a helical screw expander and silica gel–water adsorption chiller, etc., was proposed and extensively investigated. The system has the merits of effecting the power generation cycle at lower temperature level with solar energy more efficiently and can provide both thermal energy and power for remote off-grid regions. A case study was carried out to evaluate an annual energy and exergy efficiency of the system under the climate of northwestern region of China. It is found that both the main energy and exergy loss take place at the parabolic trough collector, amount to 36.2% and 70.4%, respectively. Also found is that the studied system can have a higher solar energy conversion efficiency than the conventional solar thermal power generation system alone. The energy efficiency can be increased to 58.0% from 10.2%, and the exergy efficiency can be increased to 15.2% from 12.5%. Moreover, the economical analysis in terms of cost and payback period (PP) has been carried out. The study reveals that the proposed system the PP of the proposed system is about 18 years under present energy price conditions. The sensitivity analysis shows that if the interest rate decreases to 3% or energy price increase by 50%, PP will be less than 10 years.

404 小形スクリューエキスパンダの特性

404 小形スクリューエキスパンダの特性

554 追加給気を伴うスクリューエキスパンダの特性

554 追加給気を伴うスクリューエキスパンダの特性

An Analysis of Characteristics on a Helical Screw Expander Considering Dynamic Behaviors.

Helical Screw Expander is a positive displacement type fluid machine. So far, steady simulation methods were carrided out to get quantities of state between the lobes, where the internal leakage is occurred. In these simulations, quantities of state hold constant values in the admission process. However, the disagreements between the simulation and the experimental results are extended at the higher rotor speed. Therefore, the simulation method has to consider the dynamic behaviors at the admission process. In this work, the bondgraphs technique was used to predict the dynamic behavior. Hence, the bondgraphs method improved the evaluation of the performance, especially at the higher region of the rotor peripheral speed. Consequently, the effectiveness of the bondgraphs method to predict the performance on a helical screw expander is confirmed.

Performance Analysis of a Helical Screw Expander.

A helical screw expander, is a rotary positive displacement machine, is expected to adapt a small sized energy conversion machine from the waste heat or a total flow expander for the geothermal resources. So far, fundamental performance of the helical screw expander had been studied experimentalluy. But, more detail data with wide operating conditions are need to estimate the performance of the helical screw expander. In this work, we developed the simulation program, which included leakage losses and dynamic losses of the flow past through the inlet or the discharge port. Furthermore, the unsymmetrical rotor profile, which had been used in the experimental studies, is used in this performance analysis method. Simulation results are agreed with the experimental results, especially at the low speed region. Then this simulation method is applicable to evaluate the performance of a helical screw expander.

708 スクリュエキスパンダの冷凍サイクルへの適用に関する研究(オーガナイズドセッション : 流体工学2)

708 スクリュエキスパンダの冷凍サイクルへの適用に関する研究(オーガナイズドセッション : 流体工学2)

Analysis of Screw-Expander Performance

The paper examines the thermodynamic processes of a helical screw-expander that operates with dry saturated steam at its inlet. The work output of the screw-expander is analysed using a simple ‘pseudo-polytropic’ index. Using the available experimental data from the literature, an empirical model for the prediction of work using the ‘pseudo-polytropic’ indices is formulated. The expansion indices are expressed in terms of built-in volumetric and pressure ratios; how they are formulated is usually given in an expander specification. Based on the empirical model, there is a good agreement between the experimental work and the predicted values.

Technical and economic overview of geothermal atmospheric exhaust and condensing turbines, binary cycle and biphase plant

This paper is intended to provide a broad overview of the technical and economic aspects of small geothermal generating plants. This includes consideration of conventional steam turbines with atmospheric or condensing exhaust, binary cycle and biphase plant. A further total flow device, the helical screw expander, is currently under development by the Hydrothermal Power Company and Jet Propulsion Laboratory (U.S.A.) but has not been included as it is not yet in commercial production.

Study on Fundamental Performance of Helical Screw Expander

This work is description of a fundamental study to evaluate and characterize a helical screw expander, which is a rotary positive displacement type machine, for small energy conversion machines. Ideal helical screw expander, in which the working fluid is supposed to expand adiabatically without losses, is investigated and compared with experimental results. Using the indicator diagram technique, the characteristics of internal leakage has been investigated.