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.

scholarly journals Heating performance of a laboratory pilot-plant combining heat exchanger and air scrubber for animal houses

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manuel S. Krommweh ◽  
Wolfgang Büscher
Keyword(s):  
Heat Exchanger ◽  
Air Temperature ◽  
Pilot Plant ◽  
Animal Husbandry ◽  
Operating Costs ◽  
Small Scale ◽  
Heating Performance ◽  
Livestock Buildings ◽  
Reduce Emissions ◽  
Recuperative Heat Exchanger

AbstractExhaust air treatment systems (EATS) are used in animal husbandry to reduce emissions. However, EATS are associated with high acquisition and operating costs. Therefore, a plant technology is being developed that integrates a recuperative heat exchanger into a biological air scrubber. The overall aim is to reduce total costs of livestock buildings with EATS by saving heating costs and to improve animal environment. In this study, a special pilot-plant on a small-scale, using clean exhaust air, was constructed to evaluate the heating performance on laboratory scale. Three assembly situations of the heat exchanger into trickle-bed reactor were part of a trial with two different defined air flow rates. In all three assembly situations, preheating of cold outside air was observed. The heating performance of the assembly situation with the sprayed heat exchanger arranged below showed an average of 4.4 kW at 1800 m3 h−1 (outside air temperature range 0.0–7.9 °C). This is up to 18% higher than the other two experimental setups. The heating performance of the pilot-plant is particularly influenced by the outside air temperature. Further research on the pilot-plant is required to test the system under field conditions.

scholarly journals REVIEW OF ORGANIC RANKINE CYCLE USED IN SMALL- SCALE APPLICATION

2020 ◽  
Vol 7 (1) ◽  
pp. 52-63
Author(s):  
Ali A. F. Al-Hamadani ◽  
Aya Haitham. A. Kareem
Keyword(s):  
Heat Exchanger ◽  
High Efficiency ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Small Scale ◽  
Heat Sources ◽  
Radial Turbine ◽  
Temperature Method ◽  
Energy From Waste

Organic Rankine cycle an alternative way of generating energy from waste heat, fuel and gases at low-temperature. Method (ORC) proved successful and high efficiency to reduce environmental pollution, fuel consumption and convert low to medium heat sources. The paper will be presenting a review investigation on the organic Rankine cycle(ORC), cycle Background, (ORC) configuration, and selecting of working fluids and experimental studied of expansion apparatuses, which are classified into two type volumetric type such as (expander of rotary vane, scroll, reciprocating piston expander and screw) velocity kind (for example axial and radial turbine). Heat exchanger and expander apparatuses are considered economically expensive parts in (ORC).

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.

Clustering-Triggered Efficient Room Temperature Phosphorescence from Nonconventional Luminophores

2019 ◽  
Author(s):  
Shuyuan Zheng ◽  
Taiping Hu ◽  
Xin Bin ◽  
Yunzhong Wang ◽  
Yuanping Yi ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Efficiency ◽  
Spin Orbit Coupling ◽  
Design Rationale ◽  
Emission Mechanism ◽  
Room Temperature Phosphorescence ◽  
Electronic Interactions ◽  
Energy Gaps ◽  
Theoretical Results

Pure organic room temperature phosphorescence (RTP) and luminescence from nonconventional luminophores have gained increasing attention. However, it remains challenging to achieve efficient RTP from unorthodox luminophores, on account of the unsophisticated understanding of the emission mechanism. Here we propose a strategy to realize efficient RTP in nonconventional luminophores through incorporation of lone pairs together with clustering and effective electronic interactions. The former promotes spin-orbit coupling and boost the consequent intersystem crossing, whereas the latter narrows energy gaps and stabilizes the triplets, thus synergistically affording remarkable RTP. Experimental and theoretical results of urea and its derivatives verify the design rationale. Remarkably, RTP from thiourea solids with unprecedentedly high efficiency of up to 24.5% is obtained. Further control experiments testify the crucial role of through-space delocalization on the emission. These results would spur the future fabrication of nonconventional phosphors, and moreover should advance understanding of the underlying emission mechanism.<br>

PROCUREMENT STRATEGY AS A TOOL FOR MANAGING A FUEL AND ENERGY COMPLEX ENTERPRISE

2020 ◽  
Vol 1 (10) ◽  
pp. 13-25
Author(s):  
A. P. SOKOLOV ◽  
◽  
L. P. VASILIEVA ◽  
I. V. BRATKO ◽  
◽  
...  
Keyword(s):  
Strategic Planning ◽  
National Economy ◽  
High Efficiency ◽  
Management Tool ◽  
Market Environment ◽  
External Market ◽  
Energy Complex ◽  
Multi Stage ◽  
Procurement Strategy ◽  
Number Of Branches

The authors consider the issues of forming a procurement strategy for enterprises of the fuel and energy complex (FEC) as a management tool. The study begins with a review of the categories of strategy, purchasing, and risk. Based on the generalization and interpretation of the obtained knowledge, the author's model of procurement strategy for enterprises of the fuel and energy complex is proposed, which differs from the existing ones in that it simultaneously acts as a means of connecting the enterprise with the external market environment. The strategy has a complex multi-stage character with many elements. Through detailed strategic planning can be achieved high efficiency of the procurement activities of enterprises of fuel and energy. The proposed algorithm can form the basis of an unlimited number of branches of the national economy.

Integrated Design and Multi-Objective Optimization of a Single Stage Heat-Pump Turbocompressor

2013 ◽  
Author(s):  
J. Schiffmann
Keyword(s):  
Design Optimization ◽  
High Efficiency ◽  
Integrated Design ◽  
Heat Pumps ◽  
Small Scale ◽  
Multi Objective Optimization ◽  
Design Constraints ◽  
Multi Objective ◽  
Wide Range ◽  
Standard Design

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.

scholarly journals Skyrmion Logic-In-Memory Architecture for Maximum/Minimum Search

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 155
Author(s):  
Luca Gnoli ◽  
Fabrizio Riente ◽  
Marco Vacca ◽  
Massimo Ruo Roch ◽  
Mariagrazia Graziano
Keyword(s):  
High Efficiency ◽  
Digital Design ◽  
Control Logic ◽  
Minimum Number ◽  
Physical Simulations ◽  
Good Energy ◽  
Logic Functions ◽  
Time And Energy ◽  
Cmos Implementation ◽  
Maximum Minimum

In modern computing systems there is the need to utilize a large amount of data in maintaining high efficiency. Limited memory bandwidth, coupled with the performance gap between memory and logic, impacts heavily on algorithms performance, increasing the overall time and energy required for computation. A possible approach to overcome such limitations is Logic-In-Memory (LIM). In this paper, we propose a LIM architecture based on a non-volatile skyrmion-based recetrack memory. The architecture can be used as a memory or can perform advanced logic functions on the stored data, for example searching for the maximum/minimum number. The circuit has been designed and validated using physical simulations for the memory array together with digital design tools for the control logic. The results highlight the small area of the proposed architecture and its good energy efficiency compared with a reference CMOS implementation.

scholarly journals Fabrication of freestanding Pt nanowires for use as thermal anemometry probes in turbulence measurements

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Hai Le-The ◽  
Christian Küchler ◽  
Albert van den Berg ◽  
Eberhard Bodenschatz ◽  
Detlef Lohse ◽  
...  
Keyword(s):  
Room Temperature ◽  
Fluid Velocity ◽  
Current Mode ◽  
Constant Current ◽  
Small Scale ◽  
Turbulence Measurements ◽  
High Dynamic ◽  
Scale Turbulence ◽  
Constant Current Mode ◽  
Pt Nanowires

AbstractWe report a robust fabrication method for patterning freestanding Pt nanowires for use as thermal anemometry probes for small-scale turbulence measurements. Using e-beam lithography, high aspect ratio Pt nanowires (~300 nm width, ~70 µm length, ~100 nm thickness) were patterned on the surface of oxidized silicon (Si) wafers. Combining wet etching processes with dry etching processes, these Pt nanowires were successfully released, rendering them freestanding between two silicon dioxide (SiO2) beams supported on Si cantilevers. Moreover, the unique design of the bridge holding the device allowed gentle release of the device without damaging the Pt nanowires. The total fabrication time was minimized by restricting the use of e-beam lithography to the patterning of the Pt nanowires, while standard photolithography was employed for other parts of the devices. We demonstrate that the fabricated sensors are suitable for turbulence measurements when operated in constant-current mode. A robust calibration between the output voltage and the fluid velocity was established over the velocity range from 0.5 to 5 m s−1 in a SF6 atmosphere at a pressure of 2 bar and a temperature of 21 °C. The sensing signal from the nanowires showed negligible drift over a period of several hours. Moreover, we confirmed that the nanowires can withstand high dynamic pressures by testing them in air at room temperature for velocities up to 55 m s−1.

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