Optimal theoretical design of 2-D microscale viscous pumps for maximum mass flow rate and minimum power consumption

In this investigation an attempt is made to find the best hub to tip ratio, the maximum number of blades, and the best angle of attack of an axial fan with flat blades at a fixed rotational speed for a maximum mass flow rate in a steady and turbulent conditions. In this study the blade angles are varied from 30 to 70 degrees, the hub to tip ratio is varied from 0.2 to 0.4 and the number of blades are varied from 2 to 6 at a fixed hub rotational speed. The results show that, the maximum flow rate is achieved at a blade angle of attack of about 45 degrees for when the number of blades is set equal to 4 at most rotational velocities. The numerical results show that as the hub to tip ratio is decreased, the mass flow rate is increased. For a hub to tip ratio of 0.2, and an angle of attack around 45 degrees with 4 blades, a maximum mass flow rate is achieved.

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Capillary trees for passive pumping water

Journal of Physics D Applied Physics ◽

10.1088/1361-6463/ac40ba ◽

2021 ◽

Author(s):

Xuewei Zhang ◽

Sylvie Lorente

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Capillary Flow ◽

Search Algorithm ◽

Geometrical Parameters ◽

Maximum Mass ◽

Capillary Flows ◽

The Impact ◽

Fixed Network

Abstract Capillary flows are an attractive feature for passive water harvesting as they require no external driving force to pull the fluid out within the capillary network. Here we analyze the architecture of capillary flow networks in steady state, and the impact of the network morphology on the maximum mass flow rate that can be extracted for a fixed network volume and fixed network footprint. We develop a search algorithm to test the possible location of all the junction and bifurcation nodes and the changes in diameter ratios with the objective of obtaining the maximum mass flow rate from the network. We define the Capillary Strength CS as a local indicator to determine the geometrical parameters of each conduct that allow to sustain the overall mass flow rate. It is shown that the diameter ratio of connected tubes for maximum mass flow rate depends on the distance from the network outlet, and therefore does not follow the Hess-Murray’s law. The superiority of dendritic architectures in the roots and canopy branches of the capillary trees is demonstrated.

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Effect of Rotational Velocity and Blade Angle of Attack on Mass Flow Rate in an Axial Fan at a Fixed Hub to Tip Ratio

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2008-55186 ◽

2008 ◽

Author(s):

Mohammad J. Izadi

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Rotational Velocity ◽

Angle Of Attack ◽

Maximum Flow ◽

Maximum Mass ◽

Blade Angle ◽

Axial Fan ◽

Very High

In this investigation an attempt is made to find the best rotational velocity and the best angle of attack of a flat blade at a fixed hub to tip ratio for a maximum mass flow rate in an axial fan in a steady and turbulent conditions. In this study the blade angles are varied from 10 to 80 degrees and the rotational velocity is varied from 500 to 2500 RPM (50 to 200 rad/sec) for a number of blades from 2 to 6, at a fixed hub to tip ratio. The results show that, the maximum flow rate is achieved at the blade angle of attack of about 45 degrees when the number of blades is set equal to 4 at most rotational velocities. The numerical results show that as the rotational velocity increased, the mass flow rate increased, but at very high rotational velocities the mass flow rate remained constant.

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Prediction of Performance Equations for Household Compressors Depending on Manufacturing Data for Refrigerators and Freezers

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.818.184 ◽

2016 ◽

Vol 818 ◽

pp. 184-209

Author(s):

Louay Abdalazez Mahdi ◽

Emad Esmaael Habib ◽

Laith Abdalmunam

Keyword(s):

Power Consumption ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Cooling Capacity ◽

Surface Fitting ◽

Temperature Cycle ◽

Evaporator Temperature ◽

Base Points ◽

Swept Volume

A semi-empirical model has been investigated to represent household compressors. The model based on calorimeter data for two distinguished brand (Danfoss and Electrolux CUBIGEL) and compared with eight brands consisting of ninety compressors model. The calorimeter data are correlated (according to ARI standard 540-90 [1] and working refrigeration temperature cycle for ASHRAE Technical Committee 8.9[2]) as a function of refrigerant saturated evaporating temperatures from (-35 to 10) °C and swept volume range (2.24-11.15) cm3 keeping of the refrigerant saturated condensing temperature constant at 54.5 °C. The correlations were found with ten-coefficient polynomial by using Matlab software – surface fitting method for cooling capacity, power consumption, and refrigerant mass flow rate.In addition, other equations for cooling capacity, power consumption, and refrigerant mass flow rate at-23.3 °C evaporator temperature, 54.4 °C condenser temperature, and 32 °C temperature for liquid line which is the base points of the refrigerator cycle according to ASHRAE[2] , cover the range (2.42-11.15) cm3 swept volume which are created to quick choose the proper compressor.The result indicated that the surface fitting models are accurate within ± 15% deviation of compressors data of seventy-two models for cooling capacity, fifty models for power, and twenty-five models for refrigerant mass flow rate.

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Multi Parameter Estimation in an Induced Draft Cooling Tower Using Genetic Algorithm

Volume 8: Heat Transfer and Thermal Engineering ◽

10.1115/imece2016-66864 ◽

2016 ◽

Cited By ~ 1

Author(s):

Kuljeet Singh ◽

Ranjan Das

Keyword(s):

Genetic Algorithm ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Optimization Algorithm ◽

Cooling Tower ◽

Design Variables ◽

Minimum Power Consumption ◽

Controlling Variables ◽

The Cost

Considering the need of performance control in engineering systems, this work presents a methodology to predict the controlling variables to control the performance of an induced draft cooling tower. At first, the set of experiments have been conducted with the variation of mass flow rate of water and air under identical ambient conditions. The experimental data for temperatures at different locations has been collected using data acquisition system (by National Instruments) in conjunction with LABVIEW™. Thereafter, relevant 3rd order empirical correlations of range and approach have been developed using the experimental readings. Depending upon the pertinent requirement, it is required to operate the cooling tower at certain combination of mass flow rate of water and air to fulfill the required output. Based upon the user requirement, the correlations are further employed to construct relevant constraint functions using the least square technique. In order to meet a desired performance (say either a given range, approach or optimum operation) of the cooling tower, the retrieval of design variables (water and air flow rates) has been carried out using an inverse optimization methodology to ensure minimum power consumption. The Genetic Algorithm (GA) is used as an optimization algorithm that minimizes the objective function along with given constraint. The optimization algorithm simultaneously predicts the possible combination of mass flow rate of water and air (control or design variables) in order to meet the given requirement. Further, the methodology avoids multiple combinations of controlling variables that satisfies a particular requirement. Therefore, the user can select an optimum combination that results in minimum power consumption. Moreover, if the cost involved in the cooling tower is considered, it is directly proportional to the range (difference between water inlet and outlet temperatures), whereas, at the same time, the cost is inversely proportional to the approach (difference between outlet water temperature and inlet air wet bulb temperature). In many applications like HVAC (heating, ventilating and air conditioning), chillers, cold storage plants and many more, lower cooling water temperature (at system inlet) is preferable in order to enhance the system efficiency. On the other hand, lower water outlet temperature from the cooling tower for a given water inlet temperature (at tower inlet) means either high range of the tower or low approach, consequently increasing the tower operating cost. Therefore, in order to save the cost involved in cooling tower operation, a compromise between the range and the approach has to be maintained to achieve an optimum performance. So, this method can be also used to predict the optimum operating parameters ensuring the possible optimum performance from the cooling tower under a given set of operating conditions.

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Theoretical and Numerical Analysis on the Temperature Drop and Power Consumption of a Pre-Swirl System

Volume 5A: Heat Transfer ◽

10.1115/gt2016-56742 ◽

2016 ◽

Cited By ~ 2

Author(s):

Gaowen Liu ◽

Heng Wu ◽

Qing Feng ◽

Songling Liu

Keyword(s):

Theoretical Analysis ◽

Power Consumption ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Temperature Drop ◽

Cover Plate ◽

Radial Location ◽

Total Temperature ◽

Cooling Air

As a component of delivering cooling air to turbine rotor blade at appropriate pressure, temperature and mass flow rate, pre-swirl system is very important to the cooling of turbine blades. It is attractive to the designers and scholars for its potential ability to reduce relative total temperature of cooling air as large as 100K. A pre-swirl system is actually an aero-thermodynamic system with energy transformation between work and heat. Theoretical analysis was carried out on an isentropic pre-swirl system to deduce equations for ideal temperature drop and power consumption. For an actual pre-swirl system, correlation between the actual temperature drop and power consumption was deduced, and a temperature drop effectiveness was defined also. Theoretical analysis shows that the system’s temperature drop increases linearly with the reduction of the power consumption. Numerical models were derived from a real engine pre-swirl system with small simplification. Standard k-ε turbulence model and Frozen-Rotor approach were applied in the three dimensional steady simulations. Inlet total pressure and total temperature, outlet static pressure, mass flow rate delivered to the blade and rotating speed of rotor were kept to be fixed for all the models. The influences of heat transfer and sealing flow coming from the inner seal were ignored in the simulations. Section averaged parameters like pressure, swirl ratio and total enthalpy were presented at each typical station throughout the flow path. The relationship between the temperature drop and the power consumption of all the models has been verified to be consistent with the deduced formula. For the pre-swirl system with low radial location of nozzle, these measures, such as adding impellers in the cover-plate cavity and inclining the receiver hole, were taken to reduce the power consumption and enlarge the temperature drop obviously. For this specific pre-swirl system, models with high radial location of nozzle are more recommended to decrease the loss caused by the large circumferential velocity difference between the airflow and the rotor.

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Experimental Analysis of Internal Heat Exchanger for Automotive A/C System

ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, Volume 2 ◽

10.1115/esda2010-24485 ◽

2010 ◽

Cited By ~ 2

Author(s):

Salman Bahrami ◽

Hasan Mohammad Beigi ◽

Mohammad Hosein Sabour

Keyword(s):

Heat Exchanger ◽

Power Consumption ◽

Mass Flow Rate ◽

Air Temperature ◽

Mass Flow ◽

Flow Rate ◽

Internal Heat ◽

Coefficient Of Performance ◽

Internal Heat Exchanger ◽

Compressor Power

In this paper, a new designed internal heat exchanger (suction-liquid line heat exchanger) for R134a automotive air conditioning system is proposed, and is studied experimentally. The approval is done by calorimeter test apparatus, which provides conditions close to real automotive A/C system operation. In this design, the high-pressure liquid passes through central channel and the low-pressure vapor flows in several parallel channels in the opposite direction. The results show that in all conditions, internal heat exchanger adoption will increase the condenser real capacity. Therefore, smaller condensers can be used to reach the same capacities. Using the designed internal heat exchanger will decrease the needed mass flow rate. In a constant mass flow rate, internal heat exchanger adoption will increase evaporator capacity. In all concluded tests, the compressor power consumption was decreasing by internal heat exchanger adoption; it was intensifying at higher air temperature passing through the condenser. Using this internal heat exchanger will decrease compressor power consumption up to 6%, and will increase mostly the coefficient of performance. The condenser higher air temperature will increase the coefficient of performance and its improvement with internal heat exchanger. In this case the coefficient of performance can increase up to 8.4%, and will enhance subcooled degree at expansion valve inlet up to 12.8°C.

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