Determination of Flow Rate Characteristics of Pneumatic Solenoid Valves Using an Isothermal Chamber

2004 ◽  
Vol 126 (2) ◽  
pp. 273-279 ◽  
Author(s):  
Kenji Kawashima ◽  
Yukio Ishii ◽  
Tatsuya Funaki ◽  
Toshiharu Kagawa
Keyword(s):  
Heat Transfer ◽  
Critical Pressure ◽  
Pressure Ratio ◽  
Pressure Change ◽  
Pressure Response ◽  
Heat Transfer Area ◽  
New Methods ◽  
Upstream Pressure ◽  
Pneumatic Valves

In this paper, two new methods for obtaining the sonic conductance and the critical pressure ratio of pneumatic valves are proposed. Both methods use a chamber that can approximate isothermal conditions. This was achieved by filling the chamber with metal wire, which creates a larger heat transfer area and heat transfer coefficient. The sonic conductance and the critical pressure ratio are obtained by measuring the pressure in the chamber during charging and discharging. These methods take only seconds to perform and require less energy than the ISO 6358 procedure. The major factor in the error for the pressure response during the charging of the isothermal chamber is the upstream pressure change. Nevertheless, the sonic conductance can be determined within a 3% uncertainty. In addition, the sonic conductance calculated from the pressure response during the discharging of the chamber can be determined within a 1.2% uncertainty.

Heat Transfer Effects on Dynamic Pressure Response of Pneumatic Vacuum Circuit

2011 ◽  
Author(s):  
Zhonghua Guo ◽  
Xiaoning Li ◽  
Toshiharu Kagawa
Keyword(s):  
Heat Transfer ◽  
Vacuum Chamber ◽  
Dynamic Pressure ◽  
Isothermal Condition ◽  
Pressure Response ◽  
Heat Transfer Area ◽  
Transfer Effects ◽  
Vacuum Degree ◽  
Long Time ◽  
Heat Transfer Effects

In the industrial conveying systems powered by pneumatic ejector, the dynamic pressure response of vacuum circuit is critical to systematic strategic planning. This paper analyzes heat transfer effects on dynamic pressure response. Experiments are carried out in temperature measurement with the stop method. The heat transfer ratio is obtained when the air is entrained from the acrylic chamber under the vacuum condition. The decreasing value of the air temperature inside the vacuum chamber is concerned with ejector flow rate characteristics, the material of the vacuum chamber and heat transfer area. The heat transfer area could be enlarged with copper wires stuffed in the chamber and the isothermal condition is realized. The suction process in such isothermal chamber is then compared with that in the acrylic chamber. The pressure response is faster in the acrylic chamber at the beginning of the suction process but a long time to reach final vacuum degree for temperature recovery.

Nonideal Gas Effects for the Venturi Meter

1991 ◽  
Vol 113 (2) ◽  
pp. 301-304 ◽  
Author(s):  
W. Bober ◽  
W. L. Chow
Keyword(s):  
Mass Flow Rate ◽  
Flow Rate ◽  
Critical Pressure ◽  
Pressure Ratio ◽  
Maximum Flow ◽  
Expansion Factor ◽  
Nonideal Gas ◽  
Percent Difference ◽  
The Ideal

A method for treating nonideal gas flows through a venturi meter is described. The method is an extension of a previous study reported in an earlier paper. The method involves the determination of the expansion factor which may then be used to determine the mass flow rate through the venturi meter. The method also provides the means for determining the critical pressure ratio as well as the maximum flow rate per unit throat area. The Redlich-Kwong equation of state is used, which allows for closed form expressions for the specific heat at constant volume and the change in entropy. The Newton-Raphson method is used to determine the temperature and specific volume at the throat. It is assumed that the following items are known: the upstream temperature and pressure and the ratio of the throat pressure to the upstream pressure. Results were obtained for methane gas. These results indicate that for the cases considered, the use of the ideal gas expression for the expansion factor would lead to an error in the determination of the mass flow rate; the error increases as the throat to inlet pressure ratio decreases. For the example reported in this study, the maximum percent difference in the critical pressure ratio between the ideal and nonideal gases was 5.81 percent, while the maximum percent difference in the maximum flow rate per unit throat area was 7.62 percent.

The Regenerative Criteria of an Irreversible Brayton Heat Engine and its General Optimum Performance Characteristics

2005 ◽  
Vol 128 (3) ◽  
pp. 216-222 ◽  
Author(s):  
Yue Zhang ◽  
Congjie Ou ◽  
Bihong Lin ◽  
Jincan Chen
Keyword(s):  
Heat Transfer ◽  
Power Output ◽  
Pressure Ratio ◽  
Heat Engine ◽  
Optimal Performance ◽  
Performance Characteristics ◽  
Heat Transfer Area ◽  
Total Heat Transfer ◽  
Heat Engines ◽  
Compression And Expansion

An irreversible cycle model of the Brayton heat engine is established, in which the irreversibilities resulting from the internal dissipation of the working substance in the adiabatic compression and expansion processes and the finite-rate heat transfer in the regenerative and constant-pressure processes are taken into account. The power output and efficiency of the cycle are expressed as functions of temperatures of the working substance and the heat sources, heat transfer coefficients, pressure ratio, regenerator effectiveness, and total heat transfer area including the heat transfer areas of the regenerator and other heat exchangers. The regenerative criteria are given. The power output is optimized for a given efficiency. The general optimal performance characteristics of the cycle are revealed. The optimal performance of the Brayton heat engines with and without regeneration is compared quantitatively. The advantages of using the regenerator are expounded. Some important parameters of an irreversible regenerative Brayton heat engine, such as the temperatures of the working substance at different states, pressure ratio, maximum value of the pressure ratio, regenerator effectiveness and ratios of the various heat transfer areas to the total heat transfer area of the cycle, are further optimized. The optimal relations between these parameters and the efficiency of the cycle are presented by a set of characteristic curves for some assumed compression and expansion efficiencies. The results obtained may be helpful to the comprehensive understanding of the optimal performance of the Brayton heat engines with and without regeneration and play a theoretical instructive role for the optimal design of a regenerative Brayton heat engine.

Determination of effective heat transfer area on vertical surfaces subject to spray and impinging jet

2020 ◽  
pp. 116303
Author(s):  
Jessica Kansy ◽  
Thomas Kalmbach ◽  
André Loges ◽  
Joachim Treier ◽  
Thomas Wetzel ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Impinging Jet ◽  
Heat Transfer Area ◽  
Effective Heat

Determination of Optimum Heat Transfer Area for Vacuum Evaporators in Ships

2004 ◽  
Vol 41 (01) ◽  
pp. 17-21
Author(s):  
Recep Ozturk ◽  
Ahmet Dursun Alkan
Keyword(s):  
Heat Transfer ◽  
Thermodynamic Analysis ◽  
Analytical Method ◽  
Load Capacity ◽  
Design Parameters ◽  
Heat Transfer Area ◽  
Optimum Heat ◽  
Definition Of ◽  
Significant Factors

In ships, utility water can be produced from seawater through a vacuum evaporator instead of supplying from ports, and this solution will certainly allow extra load capacity for ships. In this application, the size of vacuum evaporators and their heat transfer areas are significant factors in terms of investment costs and the volume or weight capacity, which for ships are particularly important parameters. In the present research, the change of heat transfer areas of vacuum evaporators that are used to produce utility water was analyzed with respect to design parameters and the results from the thermodynamic analysis were evaluated to define the optimum heat transfer area. Because an analytical method has been employed in the definition of the optimum heat transfer area, the influence of design parameters on the evaporatorsize can be identified easily.

INFLUENCE OF HEAT TREATMENT OF MOUNTAIN MASSIVE ON TEMPERATURE MODE OF GEOTHERMAL CIRCULATION SYSTEM

2018 ◽  
pp. 44-50
Author(s):  
Yu. P. Morozov
Keyword(s):  
Heat Transfer ◽  
Operating Time ◽  
Fluid Motion ◽  
Coolant Temperature ◽  
Circulation System ◽  
Thermal Processes ◽  
Temperature Mode ◽  
Heat Influx ◽  
Stationary Heat Transfer

Based on the solution of the problem of non-stationary heat transfer during fluid motion in underground permeable layers, dependence was obtained to determine the operating time of the geothermal circulation system in the regime of constant and falling temperatures. It has been established that for a thickness of the layer H <4 m, the influence of heat influxes at = 0.99 and = 0.5 is practically the same, but for a thickness of the layer H> 5 m, the influence of heat inflows depends significantly on temperature. At a thickness of the permeable formation H> 20 m, the heat transfer at = 0.99 has virtually no effect on the thermal processes in the permeable formation, but at = 0.5 the heat influx, depending on the speed of movement, can be from 50 to 90%. Only at H> 50 m, the effect of heat influx significantly decreases and amounts, depending on the filtration rate, from 50 to 10%. The thermal effect of the rock mass with its thickness of more than 10 m, the distance between the discharge circuit and operation, as well as the speed of the coolant have almost no effect on the determination of the operating time of the GCS in constant temperature mode. During operation of the GCS at a dimensionless coolant temperature = 0.5, the velocity of the coolant is significant. With an increase in the speed of the coolant in two times, the error changes by 1.5 times.

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