Cycle Optimization and Comparison of Ideal Thermal Cycles for Maximum Specific Output

1994 ◽  
Vol 22 (3) ◽  
pp. 177-190
Author(s):  
B. Agnew ◽  
A. Anderson ◽  
T. H. Frost
Keyword(s):  
Power Generation ◽  
Thermal Efficiency ◽  
Design Parameters ◽  
Work Output ◽  
Temperature Ratio ◽  
Thermodynamic Cycles ◽  
Rate Processes ◽  
Important Design ◽  
Cycle Temperature ◽  
Selection Of

The thermal efficiencies of several thermodynamic cycles are evaluated and compared for the condition of maximum specific net work output for a specified cycle temperature ratio. It is shown at this condition that the efficiencies of all of the cycles are very similar and that an objective selection of a cycle for a particular application cannot be made on the basis of thermal efficiency alone. The different cycles are then compared with respect to other important design parameters for the optimized condition and comments are made with regard to power generation and the associated controlling rate processes.

Comparative Thermodynamics for Brayton and Rankine Cycles

1990 ◽  
Vol 112 (1) ◽  
pp. 94-99 ◽  
Author(s):  
E. W. Beans
Keyword(s):  
Thermodynamic Model ◽  
Thermal Efficiency ◽  
Unit Volume ◽  
Work Conditions ◽  
Comparison Analysis ◽  
Independent Variables ◽  
Equal Work ◽  
Maximum Work ◽  
Cycle Temperature ◽  
Selection Of

The thermal efficiency, work per unit mass, and work per unit volume of the simple Rankine and Brayton cycles are expressed in terms of seven independent variables using a simplified thermodynamic model. By requiring equal efficiency, equal work conditions, and the same maximum cycle temperature for both cycles, two necessary relationships are established between the seven independent variables. These two relationships along with two maximum work conditions produce a method for comparing required and selected properties. These comparisons provide useful guidelines for the selection of the cycle and cycle fluids. The comparison analysis shows that for a given application the more attractive cycle is strongly dependent upon the fluids selected.

Theory on Thermal Probe Arrays for the Distinction Between the Convective and the Perfusive Modalities of Heat Transfer in Living Tissues

1987 ◽  
Vol 109 (4) ◽  
pp. 346-352 ◽  
Author(s):  
H. Arkin ◽  
K. R. Holmes ◽  
M. M. Chen
Keyword(s):  
Heat Transfer ◽  
Short Pulse ◽  
Bioheat Transfer ◽  
Design Parameters ◽  
Bioheat Equation ◽  
Thermal Probe ◽  
Living Tissues ◽  
Improved Model ◽  
Important Design ◽  
Selection Of

Recent suggestions for an improved model of heat transfer in living tissues emphasize the existence of a convective mode due to flowing blood in addition to, or even instead of, the perfusive mode, as proposed in Pennes’ “classic” bioheat equation. In view of these suggestions, it might be beneficial to develop a technique that will enable one to distinguish between these two modes of bioheat transfer. To this end, a concept that utilizes a multiprobe array of thermistors in conjunction with a revised bioheat transfer equation has been derived to distinguish between, and to quantify the perfusive and convective contribution of blood to heat transfer in living tissues. The array consists of two or more temperature sensors one of which also serves to locally insert a short pulse of heat into the tissue prior to the temperature measurements. A theoretical analysis shows that such a concept is feasible. The construction of the system involves the selection of several important design parameters, i.e., the distance between the probes, the heating power, and the pulse duration. The choice of these parameters is based on computer simulations of the actual experiment.

A Contribution to the Study of Analogies of Power Transmissions in Machines

1974 ◽  
Vol 188 (1) ◽  
pp. 1-9 ◽  
Author(s):  
W. M. J. Schlösser
Keyword(s):  
Dynamic Properties ◽  
Design Parameters ◽  
Force Density ◽  
Effective Volume ◽  
Hydraulic Power ◽  
Important Design ◽  
Selection Of

In this lecture an analogy is described by means of which transmissions can be analysed and compared. Two important design parameters are the force density Δ and the effective volume V*, which can be used to analyse stationary and moving methods of transmission. With this analogy a tool is given to the designer to compare transmissions with regard to performance, controllability, size and weight, intensity of loading, dynamic properties. A beginning has been made with formulating a relation between the intensity of loading and wear phenomena (II). With this work we hope to have contributed to a sounder basis for the study and development of power transmissions and their use in machines. As mechanical, electrical, pneumatic, and hydraulic power transmissions can be compared by means of this analogy, the selection of transmissions can be made on a sounder basis.

Effiecency criterion for selection of design parameters of aerospace system

2016 ◽  
Vol 22 (2(99)) ◽  
pp. 48-51
Author(s):  
D.S. Kalynychenko ◽  
◽  
Ye.Yu. Baranov ◽  
M.V. Poluian ◽  
◽  
...  
Keyword(s):  
Design Parameters ◽  
Selection Of

scholarly journals Development of Thermal Performance Metrics for Direct Gas-Fired Circulating Heaters

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 588
Author(s):  
Benjamin C. Smith ◽  
Brett C. Ramirez ◽  
Steven J. Hoff
Keyword(s):  
Mass Flow ◽  
Measurement System ◽  
Thermal Efficiency ◽  
Performance Metrics ◽  
Standardized Test ◽  
Flow System ◽  
Standard Test ◽  
Testing System ◽  
Measurement Systems ◽  
Selection Of

Many climate-controlled agricultural buildings use direct gas-fired circulating heaters (DGFCH) for supplement heat. There is no standardized test to calculate thermal efficiency for these heaters. This study aimed to develop a measurement system and analytical analysis for thermal efficiency, quantify the measurement uncertainty, and assess economics of DGFCH efficiency. The measurement system developed was similar to the ASHRAE 103 standard test stand with adaptations to connect the apparatus to the DGFCH. Two different propane measurement systems were used: input ratings < 30 kW used a mass flow system and input ratings > 30 kW used a volumetric gas meter. Three DGFCHs (21.9, 29.3, 73.3 kW) were tested to evaluate the system. Thermal efficiencies ranged from 92.4% to 100.9%. The resulting uncertainty (coverage factor of 2; ~95% Confidence Interval) ranged from 13.1% to 30.7% for input ratings of 56.3 to 11.4 kW. Key sources of uncertainty were propane and mass flow of air measurement. The economic impact of 1% difference in thermal efficiency ranged from USD $61.3 to $72.0 per heating season. Refinement of the testing system and procedures are needed to reduce the uncertainty. The application of this system will aid building designers in selection of DGFCHs for various applications.

scholarly journals Impact of Cross-Tie Properties on the Modal Behavior of Cable Networks on Cable-Stayed Bridges

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Javaid Ahmad ◽  
Shaohong Cheng ◽  
Faouzi Ghrib
Keyword(s):  
Analytical Model ◽  
Design Parameters ◽  
Reference Base ◽  
Cable Network ◽  
Cable Networks ◽  
Modal Behavior ◽  
Stiffness And Damping ◽  
Main Cables ◽  
The Impact ◽  
Selection Of

Dynamic behaviour of cable networks is highly dependent on the installation location, stiffness, and damping of cross-ties. Thus, these are the important design parameters for a cable network. While the effects of the former two on the network response have been investigated to some extent in the past, the impact of cross-tie damping has rarely been addressed. To comprehend our knowledge of mechanics associated with cable networks, in the current study, an analytical model of a cable network will be proposed by taking into account both cross-tie stiffness and damping. In addition, the damping property of main cables in the network will also be considered in the formulation. This would allow exploring not only the effectiveness of a cross-tie design on enhancing the in-plane stiffness of a constituted cable network, but also its energy dissipation capacity. The proposed analytical model will be applied to networks with different configurations. The influence of cross-tie stiffness and damping on the modal response of various types of networks will be investigated by using the corresponding undamped rigid cross-tie network as a reference base. Results will provide valuable information on the selection of cross-tie properties to achieve more effective cable vibration control.

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