Dynamic Behavior of Air Condition System and Temperature Control Analysis

A procedure for deriving a dynamic model of an air condition system was described in this paper. The system consisted of a zone, cooling coils and fan. Room thermal balance model and dynamic model of AC control system components including sensor, cooling coils and ducts, were established. This model accurately predicts the effect of inlet air temperature during closed loop control of output air temperature using chilled water flow rate as a control input. Fuzzy adaptive control (FAC) combined with proportional integral derivative (PID) control algorithms (FAC-PID) were used to control the chilled water flow rate. Computational simulations were carried out in toolbox Simulink of Matlab. The fuzzy parameters were carefully tuned to produce less oscillatory responses. The results show that the system based on FAC-PID control is capable of controlling the disturbance efficiently with less time lag and small error than PID control.

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In-Situ Resistance Coefficient Curve and Experimental Analysis of a Virtual Chilled Water Flow Meter at Air Handling Unit Level

Volume 6: Energy, Parts A and B ◽

10.1115/imece2012-87634 ◽

2012 ◽

Cited By ~ 1

Author(s):

Li Song ◽

Gang Wang ◽

Atul Swamy ◽

Gyujin Shim

Keyword(s):

Water Flow ◽

Flow Rate ◽

Water Flow Rate ◽

Control Valve ◽

Resistance Coefficient ◽

Flow Meter ◽

Control Valves ◽

Air Handling Unit ◽

Cooling Coils

In this paper, a virtual Air handling unit (AHU) level water flow meter using a control valve as a measurement device is experimentally validated through two different sizes of control valves on cooling coils. The flow through the valve is indirectly calculated using in-situ valve resistance coefficient curve, differential pressure over both the valve and its associated coil and valve stem positions. It was concluded in previous studies that the in-situ valve resistance coefficient curve is critical for determining the accuracy of the virtual valve flow meter. In this paper, an experimental approach and a theoretical approach of obtaining the in-situ valve resistance coefficient curve are introduced and as a result, accuracy of the virtual valve flow meters, using two different sizes of control valves: a smaller valve with design water flow rate of 25GPM and a larger valve with design water flow rate of 300GPM, is compared with an ultrasonic meter. The comparison show less than 4% of error over the full measurement range.

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Theoretical Prediction of Optimum Chilled Water Distribution Configuration in Air Conditioning Terminal Unit

Al-Khwarizmi Engineering Journal ◽

10.22153/kej.2018.12.006 ◽

2019 ◽

Vol 14 (2) ◽

pp. 137-146

Author(s):

Ahmed Abd Mohammed Saleh ◽

Ali Reyadh Shabeeb

Keyword(s):

Standard Deviation ◽

Water Supply ◽

Water Flow ◽

Flow Rate ◽

Air Conditioning ◽

Water Flow Rate ◽

Total Water ◽

Terminal Unit ◽

Chilled Water ◽

Valve Opening

The distribution of chilled water flow rate in terminal unit is a major factor used to evaluate the performance of central air conditioning unit. In this work, a theoretical chilled water distribution in the terminal units has been studied to predict the optimum heat performance of terminal unit. The central Air-conditioning unit model consists of cooling/ heating coil (three units), chilled water source (chiller), three-way and two-way valve with bypass, piping network, and pump. The term of optimization in terminal unit ingredient has two categories, the first is the uniform of the water flow rate representing in statically permanents standard deviation (minimum value) and the second category is the maximum heat transfer rate from all terminal units. The hydraulic and energy equations governing the performance of unit solved with the aid of FORTRAN code with considering the following parameters: total water flow rate, chilled water supply temperature, and variable valve opening. It was found that the optimum solution of three-way valve case at 8°C water supply temperature, 0.12 kg/s total water flow rate and valve opening order (valve 1: 100%, valve 2: 100% and valve 3: 75%) with total heat rate (987.92 Watt) and standard deviation (1.181E-3). Also, for the two-way valve case the results showed that the optimum condition at 8°C water supply temperature, 0.12 kg/s total water flow rate and valve opening order (valve 1: 75%, valve 2: 75% and valve 3: 50%) with total heat rate and standard deviation (717Watt) and (5.69E-4) respectively.

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Effect of pad water flow rate on evaporative cooling system efficiency in laying hen housing

Journal of Agricultural Engineering ◽

10.4081/jae.2020.1051 ◽

2020 ◽

Vol 51 (4) ◽

pp. 209-219

Author(s):

Mohamed Saied Ghoname

Keyword(s):

Water Flow ◽

Air Temperature ◽

Flow Rate ◽

Indoor Air ◽

Cooling System ◽

Water Flow Rate ◽

Comfort Zone ◽

Flow Rates ◽

Saturation Efficiency ◽

The Mean

An experiment was conducted in three commercial laying hen houses with 32-week-old hens in the summer of 2017 in a commercial farm in Gharbia Province, Egypt (31.06ºN, 31.16ºE) using an evaporative pad cooling system to determine the most suitable water flow rate for maintaining indoor air temperature within the thermal comfort zone. The experiment was conducted using three different water flow rates, i.e. 4.76, 5.65, and 6.35 L min–1.m–2, to assess the effect of different water flow rates on evaporative pad cooling system performance and determine the most suitable water flow rate for maintaining the thermal comfort zone of laying hens. The evaporative pad cooling system maintained the mean indoor air temperature below 28°C. The mean indoor air relative humidity during the experimental period ranged from 72.6 to 73.8%. The 4.76 L min–1.m–2 water flow rate resulted in the highest saturation efficiency (ca. 73.75%). In contrast, the 6.35 L min–1 m–2 water flow rate resulted in the lowest saturation efficiency (70.63%). The mean cooling energy values were 69.11, 66.0, and 66.65 kwh for water flow rates of 4.76, 5.56, and 6.35 Lmin–1m–2, respectively. The highest temperature-humidity index was 27.78°C, which indicated that birds were not stressed in all treatments.

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EFFECT OF WATER FLOW RATE ON COOLING EFFECTIVENESS AND AIR TEMPERATURE CHANGE IN EVAPORATIVE COOLING PAD SYSTEMS

Environmental Engineering and Management Journal ◽

10.30638/eemj.2016.089 ◽

2016 ◽

Vol 15 (4) ◽

pp. 827-833

Author(s):

Cengiz Karaca ◽

Yilmaz Yildiz ◽

Metin Dagtekin ◽

Zekai Gumus

Keyword(s):

Temperature Change ◽

Water Flow ◽

Air Temperature ◽

Flow Rate ◽

Evaporative Cooling ◽

Water Flow Rate ◽

Cooling Effectiveness ◽

Effect Of Water

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Experimental Study of Optimum Chilled Water Distribution Configuration in Air Conditioning Terminal Unit Using RSM Technique

Journal of Engineering ◽

10.31026/j.eng.2018.06.02 ◽

2018 ◽

Vol 24 (6) ◽

pp. 11

Author(s):

Ahmed Abd Mohammed Saleh ◽

Ali Reyadh Shabeeb

Keyword(s):

Standard Deviation ◽

Water Supply ◽

Water Flow ◽

Flow Rate ◽

Water Flow Rate ◽

Heat Rate ◽

Total Heat ◽

Total Water ◽

Chilled Water ◽

Valve Opening

The distribution of chilled water flow rate in terminal unit is an important factor used to evaluate the performance of central air conditioning unit. A prototype of A/C unit has been made, which contains three terminal units with a complete set of accessories (3-way valve, 2-way valve, and sensors) to study the effect of the main parameters, such as total water flow rate and chilled water supply temperature with variable valve opening. In this work, 40 tests were carried out. These tests were in two groups, 20 test for 3-way valve case and 20 test for 2-way valve case. These tests were performed at three levels of valve opening, total water flow rate and water supply temperature according to the design matrices established by Design of Experiment (DOE) software 'version 7' with Response surface methodology (RSM) technique. The model was conducted for each case of total heat rate, then checked statistically for adequacy by Analysis of variance (ANOVA), and found good with 95% confidence level. The results showed that the water supply temperature has a significant effect on the total heat rate of two cases. It was found that the optimum solution for maximum total heat rate and minimum flow deviation represented by standard deviation was obtained at 10°C water supply temperature, 5.5 l/min total water flow rate and 70% valve opening. The total heat rate and standard deviation were (890.249 Watt), (0.000513), respectively in three-way valve case and (743.155 Watt), (0.00277), respectively in two-way valve case. Finally, the predicted and experimental results of total heat rate and standard deviation were in agreement with a maximum error of 6.6 % in three-way valve case and 1.4% in two-way valve case.

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Effect of Water Flow on Underwater Wet Welded A36 Steel

Metals ◽

10.3390/met11050682 ◽

2021 ◽

Vol 11 (5) ◽

pp. 682

Author(s):

Eko Surojo ◽

Aziz Harya Gumilang ◽

Triyono Triyono ◽

Aditya Rio Prabowo ◽

Eko Prasetya Budiana ◽

...

Keyword(s):

Mechanical Properties ◽

Water Flow ◽

Flow Rate ◽

Water Flow Rate ◽

Physical And Mechanical Properties ◽

Shielded Metal Arc Welding ◽

Effect Of Water ◽

Bending Effect ◽

Metal Arc Welding ◽

A36 Steel

Underwater wet welding (UWW) combined with the shielded metal arc welding (SMAW) method has proven to be an effective way of permanently joining metals that can be performed in water. This research was conducted to determine the effect of water flow rate on the physical and mechanical properties (tensile, hardness, toughness, and bending effect) of underwater welded bead on A36 steel plate. The control variables used were a welding speed of 4 mm/s, a current of 120 A, electrode E7018 with a diameter of 4 mm, and freshwater. The results show that variations in water flow affected defects, microstructure, and mechanical properties of underwater welds. These defects include spatter, porosity, and undercut, which occur in all underwater welding results. The presence of flow and an increased flow rate causes differences in the microstructure, increased porosity on the weld metal, and undercut on the UWW specimen. An increase in water flow rate causes the acicular ferrite microstructure to appear greater, and the heat-affected zone (HAZ) will form finer grains. The best mechanical properties are achieved by welding with the highest flow rate, with a tensile strength of 534.1 MPa, 3.6% elongation, a Vickers microhardness in the HAZ area of 424 HV, and an impact strength of 1.47 J/mm2.

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Experimental Characterization of a Modified Airlift Pump

Volume 7: Fluids Engineering Systems and Technologies ◽

10.1115/imece2014-39899 ◽

2014 ◽

Author(s):

Afshin Goharzadeh ◽

Keegan Fernandes

Keyword(s):

Water Flow ◽

Flow Rate ◽

High Speed ◽

Water Flow Rate ◽

High Speed Photography ◽

Two Phase ◽

Inner Diameter ◽

Airlift Pump ◽

Flow Map ◽

Churn Flow

This paper presents an experimental investigation on a modified airlift pump. Experiments were undertaken as a function of air-water flow rate for two submergence ratios (ε=0.58 and 0.74), and two different riser geometries (i) straight pipe with a constant inner diameter of 19 mm and (ii) enlarged pipe with a sudden expanded diameter of 19 to 32 mm. These transparent vertical pipes, of 1 m length, were submerged in a transparent rectangular tank (0.45×0.45×1.1 m3). The compressed air was injected into the vertical pipe to lift the water from the reservoir. The flow map regime is established for both configurations and compared with previous studies. The two phase air-water flow structure at the expansion region is experimentally characterized. Pipeline geometry is found to have a significant influence on the output water flow rate. Using high speed photography and electrical conductivity probes, new flow regimes, such as “slug to churn” and “annular to churn” flow, are observed and their influence on the output water flow rate and efficiency are discussed. These experimental results provide fundamental insights into the physics of modified airlift pump.

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