scholarly journals A comparison of UK domestic water services sizing methods with each other and with empirical data

2017 ◽  
Vol 38 (6) ◽  
pp. 635-649 ◽  
Author(s):  
Jess Tindall ◽  
Jamie Pendle
Keyword(s):  
Empirical Data ◽  
Cold Water ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Design Flow ◽  
Water Volume ◽  
Practical Application ◽  
Domestic Water ◽  
Flow Rates ◽  
Water Service

Evidence suggests that domestic cold water service sizing methods in many countries around the world tend to overestimate the actual peak water volume flow rate. Oversizing domestic water service systems does waste materials and money, but it also increases the length of time that it takes for water to pass through the system which can increase water temperatures with the associated risks that presents. This paper compares the three commonly used UK domestic cold water service sizing methods and reveals variance in the methods, the design flow rates calculated and the amount of diversity applied by each method. BS EN 806 returns the lowest design flow rates of the three methods and also applies significantly greater diversity. Empirical domestic cold water service volume flow rate data from two case study buildings revealed that all three UK sizing methods significantly overestimated the peak water volume flow rates but that BS EN 806 was the closest. Additional empirical data from seven more buildings have been used to validate the data from this study and add confidence to the findings. This research provides useful evidence to help engineers select the most appropriate UK domestic cold water service sizing method and to anticipate the likely range and fluctuation of domestic cold water service flow rates. Practical application: Engineers tend to be conservative by nature and generally err on the side of caution to ensure that there is never any cause for customer complaint about their designs. This is understandable but there can be negative consequences if the full implications of such decisions are not fully understood. This paper reveals significant oversizing compared to empirical data from each of the three UK domestic water service sizing methods and highlights the reasons for this. The practical application of this paper lies in the presented results data and analysis which will help engineers make this important choice between the available sizing methods.

scholarly journals Unsteady Unidirectional MHD Flow of Voigt Fluids Moving between Two Parallel Surfaces for Variable Volume Flow Rates

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
Wei-Fan Chen ◽  
Hsin-Yi Lai ◽  
Cha'o-Kuang Chen
Keyword(s):  
Velocity Profile ◽  
Volume Flow Rate ◽  
Linear Acceleration ◽  
Mhd Flow ◽  
Volume Flow ◽  
Magnetic Field Effects ◽  
Piston Motion ◽  
Transform Method ◽  
Flow Rates ◽  
Parallel Surfaces

The velocity profile and pressure gradient of an unsteady state unidirectional MHD flow of Voigt fluids moving between two parallel surfaces under magnetic field effects are solved by the Laplace transform method. The flow motion between parallel surfaces is induced by a prescribed inlet volume flow rate that varies with time. Four cases of different inlet volume flow rates are considered in this study including (1) constant acceleration piston motion, (2) suddenly started flow, (3) linear acceleration piston motion, and (4) oscillatory piston motion. The solution for each case is elaborately derived, and the results of associated velocity profile and pressure gradients are presented in analytical forms.

scholarly journals Effects of Arterial Pco2 and Cerebrospinal Fluid Volume Flow Rate Changes on Choroid Plexus and Cerebral Blood Flow in Normal and Experimental Hydrocephalic Cats

1983 ◽  
Vol 3 (3) ◽  
pp. 369-375 ◽  
Author(s):  
S. Nakamura ◽  
G. M. Hochwald
Keyword(s):  
Blood Flow ◽  
Cerebrospinal Fluid ◽  
Cerebral Cortex ◽  
Choroid Plexus ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Brain Blood Flow ◽  
Choroidal Blood Flow ◽  
Flow Rates

The effect of changes in brain blood flow on cerebrospinal fluid (CSF) volume flow rates, and that of changes in CSF volume flow rates on brain blood flow were determined in both normal and kaolin-induced hydrocephalic cats. In both groups of cats, blood flow in grey and white matter, cerebral cortex, and choroid plexus was measured with 105Ru microspheres during normocapnia, and again with 141Ce microspheres after arterial Pco2 was either increased by 300% or decreased by 50%. Blood flow measurements were also made during perfusion of the ventricular system with mock CSF and repeated during perfusion with anisosmotic mannitol solutions to alter CSF volume flow rate. In 30 normal and 26 hydrocephalic cats, blood flow to the cerebral cortex, white matter, and choroid plexus was similar; only blood flow to the caudate nucleus was greater in normal cats. The weight of the choroid plexus from hydrocephalic cats decreased by 17%. Blood flow in the choroid plexus of all cats decreased by almost 50% following hypercapnia or hypocapnia, without a change in the CSF volume flow rate. There was no change in cerebral or choroidal blood flow when CSF volume flow rate was either increased by 170% or decreased by 80%. These results suggest that choroid plexus blood flow does not limit or affect the volume flow rate of CSF from the choroid plexus. CSF volume flow rate can be altered without corresponding blood flow changes of the brain or choroid plexus. Choroid plexus blood flow and the reactivity of both brain and choroidal blood flow to changes in arterial Pco2 were not affected by the hydrocephalus. The lower CSF formation rate of hydrocephalic cats can be attributed in part to the decrease in the mass of choroid plexus tissue.

scholarly journals Evaluation of thermal performance for natural and forced draft wet cooling tower

2019 ◽  
Vol 13 (4) ◽  
pp. 6007-6021 ◽  
Author(s):  
M. J. Al-Dulaimi ◽  
F. A. Kareem ◽  
F. A. Hamad
Keyword(s):  
Flow Rate ◽  
Thermal Performance ◽  
Cooling Tower ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Experimental Results ◽  
Water Volume ◽  
Axial Fan ◽  
Natural Draft ◽  
Forced Draft

This paper presents an experimental and numerical investigation of the thermal performance of natural draft wet cooling tower (NDWCT). The experimental investigation is carried out under natural draft condition and forced draft condition created by an axial fan. The operational parameters considered in this study are the thickness of the fill (10 and 20 cm), inlet water temperature (40, 45, and 50 °C) and inlet water volume flow rate (5.68, 7.75, and 9.46 L/min). The experimental results showed that the thermal performance is improved when the fans are used with the NDWCT. The temperature difference between inlet and outlet and effectiveness increase by 35% and 37.2%, respectively at fill thickness of 20 cm and water volume flow rate of 11.35 L/min. The temperature distribution of the air and the relative humidity were numerically simulated for both cases of natural and forced draft by employing the commercial CFD software ANSYS Fluent 15. The experimental and numerical results were validated with results from a previous work and showed a good agreement. The experimental results showed that the effectiveness increase by 22% and 30% for NDWCT and FDWCT respectively when in case of fill thickness 20 cm.

Influence of two-phase suction injection on performances of the scroll refrigeration compressor with a high-temperature shell

2021 ◽  
pp. 095440892110302
Author(s):  
Shuaihui Sun ◽  
Wang Zhe ◽  
Li Liansheng ◽  
Bu Gaoxuan
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Coefficient Of Performance ◽  
Two Phase ◽  
Flow Rates ◽  
Injection Volume ◽  
Discharge Temperature

The two-phase suction injection can reduce the discharge temperature of scroll refrigeration compressors, which work under a high-pressure ratio. The heat transfer along the pipe axis from the shell affects the two-phase suction injection significantly for the compressor with a high-temperature shell. In this paper, the suction mixing and heat transfer model was developed to calculate the heat transfer along the pipe axis from the high-temperature compressor shell. Then the model was coupled with the two-phase compressor model to obtain the compressor performance under different suction injection volume flow rates. The compressor with two-phase suction injection was tested under different injection volume flow rates to validate the model. The results indicated that the discharge temperature decreased by 2 °C when the mass injection ratio increased by 1%. As the injection volume flow rates increased, the total mass flow rate increased due to the reduction of the specific volume of the suction fluid; the input work decreased because of the reduction of specific work and the improvement of the motor's electric efficiency. The cooling capacity decreased since the cooling capacity of the injection refrigerant was wasted for cooling the suction process and the compressor shell, especially at high injection volume flow rates. The coefficient of performance reached the maximum value at the injection volume flow rate of 0.015 m3·h−1 and became lower than the coefficient of performance without injection when the injection volume flow rate raised to 0.035 m3·h−1. Hence, the two-phase suction injection can reduce the discharge temperature efficiently at low injection volume flow rates with a slight improvement of coefficient of performance.

scholarly journals C INVESTIGATION OF HEAT TRANSFER COEFFICIENT AUGMENTATION IN DIVERGENT RECTANGULAR DUCT FOR TWO PHASES FLOW (AIR-WATER)

2020 ◽  
Vol 20 (2) ◽  
pp. 111-121
Author(s):  
Hadi O . Basher ◽  
Riyadh S Al-Turaihi ◽  
Ahmed A. Shubba
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Water Volume ◽  
Maximum Heat ◽  
Air Volume ◽  
The Heat Transfer Coefficient

In this project, the flow distribution for air and water, and the enhancement of the heattransfer coefficient are experimentally studied. Experimental studies have been performed totest the influence of discharge, pitch, the height of ribs at a constant heat flux on thetemperature and pressure distributions. Along the channel of the test and the heat transfercoefficient, the water volume flow rate was about (5-12 L/min), the air volume flow rate wasabout (5.83-16.66 L/min), and heat were (80, 100,120, watt). An experimental rig wasconstructed within the test whole system. On the other hands, the channel has a divergentsection with an angle =15o with vertical axis. The study included changing in the ribs heightby using three values (12, 15, 18 mm) and changing the ribs pitch into three values (5, 8, 10mm).The results indicated an increasing in the local heat transfer coefficient as a result ofincreasing the discharge. While there was an inverse influence for the temperature distributionalong the test channel which drops when the discharge rise. The results also confirm that theincreasing in the pitch distance leads to reduce the heat transfer coefficient. Increasing theribs height increases the coefficient of heat transfer. However, the experiment heat transfercoefficient improves about (15.6 %) when the water volume flow rate increased from (5 to 12L/min), and about (18.7%) when the air volume flow rate increased from (5.83 to 16.66L/min). The best heat transfer coefficient was about (35.6 %) which can be achieved whenthe pitch decreased from (10 to 5mm). The increasing of the height from (12 to 18) mmimproves the heat transfer coefficient about (11.2 %). The best rib dimension was 18 mmheight, and 5 mm pitch, which give a maximum heat transfer coefficient (1212.02 W/m2. oC).

Axial Fan at Reversal Flow

2004 ◽  
Author(s):  
Va´clav Cyrus
Keyword(s):  
Volume Flow Rate ◽  
Axial Flow ◽  
Volume Flow ◽  
Design Flow ◽  
Flow Coefficient ◽  
Flow Rate Ratio ◽  
External Diameter ◽  
Axial Fan ◽  
Aerodynamic Loading ◽  
Reversal Flow

Flow reversal in axial fans is usually performed by the change of revolution direction and by stator vanes turning. Derived relations express the relative position of characteristics curves for reverse and normal flows. The ratio of volume flow rates at these conditions decreases with rotor blade profiles camber (aerodynamic loading) and with flow coefficient. The characteristics of two axial-flow stages A, B with different aerodynamic loading and design flow coefficient were measured on a test rig with external diameter of 600mm. Rotor diffusion factor D at mid-span of stage A and B were DR,m = 0.56 and DR,m = 0.3. Design flow coefficient was φD = 0.6 and 0.4, respectively. Theoretical deductions were confirmed by the experiment. Required volume flow rate ratio (Qrev/Qn ≥ 0.6) was reached only in the case of stage B. Detailed flow fields investigations were carried out in this case with the use of 5-hole conical probes at normal and reverse flows. The mechanism of 3D flows in blade rows could be described in these different fan working regimes.

Three-dimensional multiphase flow modeling of membrane humidifier for PEM fuel cell application

2019 ◽  
Vol 30 (1) ◽  
pp. 54-74
Author(s):  
Seyed Ali Atyabi ◽  
Ebrahim Afshari ◽  
Mohammad Yaghoub Abdollahzadeh Jamalabadi
Keyword(s):  
Flow Rate ◽  
Volume Flow Rate ◽  
Three Dimensional ◽  
Cross Flow ◽  
High Volume ◽  
Volume Flow ◽  
Dew Point ◽  
Multiphase Model ◽  
Flow Rates ◽  
Content Type

Purpose In this paper, a single module of cross-flow membrane humidifier is evaluated as a three-dimensional multiphase model. The purpose of this paper is to analyze the effect of volume flow rate, dry temperature, dew point wet temperature and porosity of gas diffusion layer on the humidifier performance. Design/methodology/approach In this study, one set of coupled equations are continuity, momentum, species and energy conservation is considered. The numerical code is benchmarked by the comparison of numerical results with experimental data of Hwang et al. Findings The results reveal that the transfer rate of water vapor and dew point approach temperature (DPAT) increase by increasing the volume flow rate. Also, it is found that the water recovery ratio (WRR) and relative humidity (RH) decrease with increasing volume flow rate. In addition, all mixed results decrease with increasing dry side temperature especially at high volume flow rates and this trend in high volume flow rates is more sensible. Although the transfer rate of water vapor and DPAT increases with increasing the wet inlet temperature, WRR and RH reduce. Increasing dew point temperature effect is more sensible at the wet side is compared with the dry side. The humidification performance will be enhanced with increasing diffusion layer porosity by increasing the wet inlet dew point temperature, but has no meaningful effect on other operating parameters. The pressure drop along humidifier gas channels increases with rising flow rate, consequently, the required power of membrane humidifier will enhance. Originality/value According to previous studies, the three-dimensional numerical multiphase model of cross-flow membrane humidifier has not been developed.

scholarly journals EXPERIMENTAL STUDY OF HEAT TRANFER AUGMENTATION USING AIR BUBBLE INJECTION AND (Al2O3 /WATER) NANOFLUID FLOW IN DOUBLE PIPE HEAT EXCHANGERS

2021 ◽  
Vol 21 (2) ◽  
pp. 96-117
Author(s):  
Dhirgham A. Alkhafaji ◽  
Hameed K. Hamzah ◽  
Haider S. Hadi
Keyword(s):  
Heat Transfer ◽  
Cold Water ◽  
Volume Flow ◽  
Hot Water ◽  
Air Bubbles ◽  
Heat Transfer Characteristics ◽  
Flow Rates ◽  
Air Bubble ◽  
Double Pipe ◽  
Pipe Heat

In the present work, an experimental study on how to increase the heat transfer coefficient (HTC) in double pipe heat exchanger (DPHE) use of a variety of Al2O3 Nano-dispersion concentrations mixed in water as base fluid with air bubble injection for counter flow arrangement under turbulent flow conditions with (Re) Reynold number range from (6000 t0 45000) . The thermal performance of (DPHE) has been enhanced with the use of two techniques. The first, is represented by adding nanoparticles to hot water (inner pipe) raising the (HTC) inside the inner tube. Increase the volume concentration cause increase in the viscosity of the nanofluid leading to increase in friction factor .Secondly is represented by Air bubble injection in outer pipe with cold water to enhance the (HTC). The mobility of air bubbles inside the water from down to up by the force of the buoyancy, and the movement of these air bubbles results in significant mixture and turbulence within the water. The variations of number of thermal units (NTU), exergy loss, dimensionless exergy and (Nu) are evaluated. The investigated parameters were cold water volume flow rates (8, 10, 12 and14) l/min, flow in outer tube. Also, three different volume flow rates of air (12, 16 and 20) l/min mixed with water in outer tube. The volume flow rates of hot water remains constant at (8 l/min) flow in inner pipe with three volumetric concentrations of given nanofluid. The results showed that the air bubble injection throughout the tube gave maximum enhancement in heat transfer characteristics followed by the no air bubble injection. Since the enhancement in heat transfer characteristics varies linearly with the volumetric concentration of Nanofluids, Nanofluids with 0.3% of Al2O3 nanoparticles gave more enhancements in (HTC) than the case without nanofluid. The Nusselt number increased about (8% - 45%).  

scholarly journals A Novel Non-Intrusive Vibration Energy Harvesting Method for Air Conditioning Compressor Unit

2021 ◽  
Vol 13 (18) ◽  
pp. 10300
Author(s):  
Chuan Choong Yang ◽  
Noor Fiqri Razqi Bin Noor Hanafi ◽  
Noor Hazrin Hany Bt Mohamad Hanif ◽  
Ahmad Faris Ismail ◽  
Hsueh-Hsien Chang
Keyword(s):  
Flow Rate ◽  
Air Conditioning ◽  
Volume Flow Rate ◽  
Piezoelectric Sensor ◽  
Volume Flow ◽  
Vibration Energy ◽  
Compressor Unit ◽  
Flow Rates ◽  
Air Volume ◽  
Custom Made

The purpose of harvesting vibration energy is to obtain clean and sustainable energy by converting vibration energy from ambient sources into a voltage output. In this work, a piezoelectric sensor, PZT-5H is attached to a 3D printed and custom-made mounting to be placed at an air conditioning condenser unit, to harvest vibration energy. The configuration of the harvester is non-intrusive, in which the harvester did not intrude into compressor unit operation. Temperature (20 °C, 22 °C, and 24 °C) and air volume flow rates (3 levels of air volume flow rate at 245 L/second, 274 L/second, and 297 L/second) were taken into consideration in this investigation. An accelerometer was first used to investigate the optimum vibration frequency in Hertz, and six locations were identified. Next, the piezoelectric sensor was mounted at these six locations, and the output root-mean-square (RMS) voltage from the piezoelectric sensor was obtained. The analysis of variance (ANOVA) indicated that temperature and air volume flow rates factors were significant. It was found that the location identified with the highest amount of vibration at 830.2 Hz from accelerometer measurement, was also the highest amount of RMS voltage, at 510.82 mV, harvested by the piezoelectric, from the temperature of 20 °C and air volume flow rates at high level (air flow volume flow rate at 297 L/second). From this work, it is feasible to utilize this novel method of harvesting waste vibration energy from the air conditioning compressor unit.

Impact of Structure Design of Artififical Upwelling Tube

2014 ◽  
Vol 496-500 ◽  
pp. 547-550 ◽  
Author(s):  
Jin Ying Leng ◽  
Jia Wang Chen ◽  
Hao Cai Huang ◽  
Shan Lin ◽  
Ming Zhou Liu ◽  
...  
Keyword(s):  
Flow Rate ◽  
Volume Flow Rate ◽  
Free Water ◽  
Deep Ocean ◽  
Structure Design ◽  
Volume Flow ◽  
Water Volume ◽  
Nutrient Distribution ◽  
Surrounding Water ◽  
Deep Ocean Water

Deep ocean water (DOW) is cold, nutrient-rich and pathogen-free water, which can be transported to the surface by upwelling. Upwelling can change the temperature and nutrient distribution of the surrounding water, hence improves the marine ecological environment and the marine primary productivity. Two lake experiments were accomplished in Qiandao Lake .The first experiment was done with hard PVC upwelling tube, while in the second experiment , the upwelling tubes with different diameters (0.5 m, 1 m, 1.5 m and 2 m) were made of nylon ,which are supported by rings. It can be concluded that upwelling ratio (the ratio of water volume flow rate and air volume flow rate) of the hard PVC upwelling tube was higher than that of soft nylon upwelling tube, and in condition of soft nylon upwelling tube, upwelling ratio of 1 m diameter tube was higher than that of others, providing important guidance for the next sea trial.

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