Development of a Small-Scale Collins Type Cryogenic Refrigerator

2003 ◽  
Author(s):  
C. L. Hannon ◽  
J. Gerstmann ◽  
J. L. Smith ◽  
J. G. Brisson ◽  
M. J. Traum
Keyword(s):  
High Efficiency ◽  
Modular Design ◽  
Low Cost ◽  
Thermodynamic Cycle ◽  
Input Power ◽  
Small Scale ◽  
Electro Magnetic ◽  
Compressor Power ◽  
Cryogenic Refrigerator ◽  
Laboratory Prototype

The feasibility of a compact, reliable, low-cost, and efficient cryocooler capable of delivering 1 Watt of cooling at 10K using less than 1kW of input power has been demonstrated analytically. The technology promises to provide highly efficient refrigeration for temperatures as low as 4K, and to be particularly beneficial for temperatures below 30K. The technical approach is to apply a high-efficiency thermodynamic cycle to a compact and reliable small-scale system by implementing a modern microprocessor into a mechanically innovative machine. The innovations of the design include “floating” piston expanders and electro-magnetic “smart” valves, which eliminate the need for mechanical linkages and reduce the input power, size, and weight of the cryocooler in an affordable modular design. It is predicted that a three-stage cryocooler operating with 15-bar helium could produce 2W of cooling at 10K while requiring less than 1kW of compressor power. A laboratory prototype is currently under development, with testing to be completed in the Fall of 2003.

Performance Evaluation of a Small Scale High Efficiency Cogeneration System

2006 ◽  
Author(s):  
Mauro Reini
Keyword(s):  
High Efficiency ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Small Scale ◽  
Performance Parameters ◽  
Cogeneration System

In recent years, a big effort has been made to improve microturbines thermal efficiency, in order to approach 40%. Two main options may be considered: i) a wide usage of advanced materials for hot ends components, like impeller and recuperator; ii) implementing more complicated thermodynamic cycle, like combined cycle. In the frame of the second option, the paper deals with the hypothesis of bottoming a low pressure ratio, recuperated gas cycle, typically realized in actual microturbines, with an Organic Rankine Cycle (ORC). The object is to evaluate the expected nominal performance parameters of the integrated-combined cycle cogeneration system, taking account of different options for working fluid, vapor pressure and component’s performance parameters. Both options of recuperated and not recuperated bottom cycles are discussed, in relation with ORC working fluid nature and possible stack temperature for microturbine exhaust gases. Finally, some preliminary consideration about the arrangement of the combined cycle unit, and the effects of possible future progress of gas cycle microturbines are presented.

scholarly journals Design and Analysis of a 35 GHz Rectenna System for Wireless Power Transfer to an Unmanned Air Vehicle

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 320
Author(s):  
Muttahid Ull Hoque ◽  
Deepak Kumar ◽  
Yves Audet ◽  
Yvon Savaria
Keyword(s):  
Antenna Array ◽  
Microwave Power ◽  
Patch Antenna ◽  
High Efficiency ◽  
Low Cost ◽  
High Gain ◽  
Input Power ◽  
Design System ◽  
Power Transfer ◽  
Critical System

In this article, the concept of a 22-kW microwave-powered unmanned aerial vehicle is presented, where the critical system architecture is analyzed and modeled for wirelessly transferring microwave power to the flying UAVs. The microwave system transmitting power at a 35 GHz frequency was found to be suitable for low-cost and compact architectures. The size of the transmitting and receiving systems are optimized to 108 m2 and 90 m2, respectively. A linearly polarized 4 × 2 rectangular microstrip patch antenna array has been designed and simulated to obtain a high gain, high directivity, and high efficiency in order to satisfy the power transfer requirement. The numerically simulated gain, directivity, and efficiency of the proposed patch antenna array are 13.4 dBi, 14 dBi, and 85%, respectively. Finally, a rectifying system (rectenna) is optimized using the Agilent advanced design system (ADS) software as a microwave power receiving system. The proposed rectenna has an efficiency profile of more than 80% for an RF input power range of 9 to 18 dBm. Moreover, the RF-to-DC conversion efficiency and DC output voltage of the proposed rectenna is 80% and 3.5 V, respectively, for a 10 dBm input power at 35 GHz with a load of 1500 Ω.

Small Scale Skid-Mounted Natural Gas to Hydrogen Production System Provides Competitive Hydrogen for China

2021 ◽  
Author(s):  
Pengfei Song ◽  
Rui Wang ◽  
Yiyan Sui ◽  
Tongwen Shan ◽  
Jianguo Hou ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Natural Gas ◽  
System Integration ◽  
Life Cycle Cost ◽  
High Efficiency ◽  
Low Cost ◽  
Small Scale ◽  
Hydrogen Generator ◽  
Technical Parameters ◽  
Full Life Cycle

Abstract Because of its convenience, high efficiency and low cost, small-scale skid-mounted hydrogen generator has become a hydrogen-production object of intense research efforts worldwide and has broad prospects in application. We analyze the technical points and difficulties in detail of this kind of on-site compact hydrogen generators from natural gas, by each section in the production process. It is suitable for integrated hydrogen refueling stations due to easy transportation and installation. Related applications are introduced by comparing the technical parameters of recent typical products in the world. Meanwhile, we calculate that the full life cycle cost of hydrogen from skid-mounted hydrogen generator from natrual gas can achieve less than 40CNY / kgH2, which is more economic than other possible hydrogen sources and transportation modes of a hydrogen refueling station. Although the advantages mentioned above, we point out that technology innovation is still desirable, especially in the process of reforming, automatic control, system integration and catalysis, to realize the minimization of skid-mounted hydrogen generators base on natural gas, for its further and wider application in the future.

Research on a Transonic Supercritical Carbon Dioxide Centrifugal Turbine

2019 ◽  
Vol 5 (4) ◽  
Author(s):  
Zehai Yang ◽  
Dan Luo ◽  
Diangui Huang
Keyword(s):  
Carbon Dioxide ◽  
Numerical Simulation ◽  
Performance Analysis ◽  
Supercritical Carbon Dioxide ◽  
Energy Conversion ◽  
High Efficiency ◽  
Low Cost ◽  
Thermodynamic Cycle ◽  
Stable Operation ◽  
Supercritical Carbon

Recently, the supercritical carbon dioxide Brayton (SCO2) cycle gained a lot of attention for its application to next-generation nuclear reactors. Turbine is the key component of the energy conversion in the thermodynamic cycle. Transonic centrifugal turbine has advantages of compatibility of aerodynamic and geometric, low cost, high power density, and high efficiency; therefore, it has opportunity to become the main energy conversion equipment in the future. In this paper, a transonic nozzle and its corresponding rotor cascade of the single-stage centrifugal turbine were designed. In addition, the three-dimensional (3D) numerical simulation and performance analysis were conducted. The numerical simulation results show that the predicted flow field is as expected and the aerodynamic parameters are in good agreement with one-dimensional (1D) design. Meanwhile, the off-design performance analysis shows that the transonic centrifugal turbine stage has wide stable operation range and strong load adaptability. Therefore, it can be concluded that the proposed turbine blade has good performance characteristics.

A Commercial Low Cost, Highly Efficient UC3842 based High Brightness LED (HBLED) Lamp

2018 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Devi Maheswaran ◽  
Sreedevi V T
Keyword(s):  
Low Cost ◽  
Current Mode ◽  
Input Power ◽  
High Brightness ◽  
Light Emitting ◽  
Extensive Simulation ◽  
Fluorescent Lamps ◽  
Led Array ◽  
Simulation Results ◽  
Laboratory Prototype

The conventional lighting sources like incandescent and fluorescent lamps are replaced by High Brightness Light Emitting Diodes (HB-LEDs). In this paper, a HBLED driver using a Single Ended Primary Inductor Converter (SEPIC) with input Power Factor Correction (PFC) is presented.  PFC is accomplished using a commercial inexpensive Peak Current Mode Controller (PCMC) IC UC3842 is newly combined with SEPIC converter. Extensive simulation results are carried out and a laboratory prototype to power 18W LED array from AC mains is implemented and the results are presented in detail.

Development and Testing of a Small-Scale Collins Type Cryocooler

2004 ◽  
Author(s):  
C. L. Hannon ◽  
B. J. Krass ◽  
J. Gerstmann ◽  
G. Chaudhry ◽  
J. G. Brisson ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Room Temperature ◽  
High Efficiency ◽  
Modular Design ◽  
Rapid Cool ◽  
Small Scale ◽  
Control Logic ◽  
Prototype Development ◽  
Multi Stage ◽  
Recuperative Heat Exchanger

Future spacecraft cooling and sensing systems will require advanced multi-stage cryocoolers capable of providing continuous cooling at multiple temperature levels ranging from 10K to 95K. A multi-stage 10K cryocooler is under development that applies modern microelectronic sophistication to achieve high efficiency in a reliable, compact design. The cryocooler is based upon a novel modification of the Collins cycle, a cycle commonly used in many high-efficiency terrestrial cryogenic machines. Innovations of the design include floating piston expanders and electromagnetic smart valves, which eliminate the need for mechanical linkages and thereby reduce the input power, size, and weight of the cryocooler in an affordable modular design. The floating piston expander and smart valves have been successfully developed in room temperature experiments using a series of proof-of-concept component prototypes. These experiments have resulted in a new warm-end configuration with improved expansion power dissipation and a new cryogenic valve design that reduces expander clearance volume and improves cold-end integration. A sophisticated LabView based control algorithm was developed over the course of the room temperature experiments that enables electronic control of the expansion cycle. Software based control will enable variable valve timing and adaptive control logic. This will result in a cryocooler with rapid cool-down and transient response capabilities as well as the ability to operate at high efficiency at arbitrary steady state load points. In parallel to this effort, a manufacturing method was developed to enable production of very long continuous lengths of small bore finned tubing. This tubing is used in the highly effective recuperative heat exchanger associated with each stage of the cryocooler. An engineering prototype has been designed that integrates the floating piston expander and recuperative heat exchanger as a functional cryocooler. The engineering prototype has been assembled and is currently undergoing development testing. This paper will present the results of the room temperature component development testing, the design of the engineering prototype, the results of initial engineering prototype development testing, and the direction of future development.

Performance Analysis and Modeling of Different Volumetric Expanders for Small-Scale Organic Rankine Cycles

2011 ◽  
Author(s):  
Stefano Clemente ◽  
Diego Micheli ◽  
Mauro Reini ◽  
Rodolfo Taccani
Keyword(s):  
Energy Recovery ◽  
Large Scale ◽  
High Efficiency ◽  
Waste Heat ◽  
Low Cost ◽  
Economic Feasibility ◽  
Small Scale ◽  
Main Research ◽  
Energy Field ◽  
Organic Rankine Cycles

In the last years one of the main research topics in energy field is represented by Organic Rankine Cycles (ORCs), due to their applicability in energy recovery from waste heat and in distributed combined heat and power (CHP) generation, particularly in small and micro scale systems. One of the key devices of the cycle is the expander: it must have a limited cost (like all the other components, in order to ensure the economic feasibility), but also a high efficiency, since the temperature of the heat source is often low and then the cycle efficiency is inherently scarce. In the first part of this paper a literature review on various positive-displacement expanders is presented, in order to outline their performances and their application field. Then, the numerical model of a volumetric reciprocating expander is implemented. This model, and another one previously developed to simulate scroll expanders, is combined with a thermodynamic model of the whole ORC system, so that a comparison between the two technologies can be carried out. The results confirm the possibility of realizing small scale energy recovery and cogeneration (CHP) systems with acceptable electrical efficiency also adopting low-cost components, directly derived from large scale industrial components.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

2019 ◽  
Author(s):  
Charlys Bezerra ◽  
Géssica Santos ◽  
Marilia Pupo ◽  
Maria Gomes ◽  
Ronaldo Silva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Pechini Method ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Calcination Temperatures ◽  
Service Lifetime

<p>Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO<sub>2</sub> and IrO<sub>2</sub> have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

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