Study on Appropriate Diameter of Centrifugal Fan Surrounded by Heat Exchanger in Air Conditioner

2017 ◽  
Author(s):  
Daiwa Sato ◽  
T. Iwase ◽  
J. Xue ◽  
K. Tsuchihashi ◽  
H. Obara ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Standard Deviation ◽  
Pressure Drop ◽  
Velocity Distribution ◽  
Flow Distribution ◽  
Centrifugal Fan ◽  
Air Conditioner ◽  
Air Conditioners ◽  
Fan Performance

To meet the demand for energy-saving air conditioners, the pressure drop must be reduced and the air velocity distribution of the heat exchanger made uniform to improve the performance of both the fan and the heat exchange cycle. To investigate the effect of the fan on the pressure drop and the velocity distribution, we changed the fan diameter and fixed the shape of the heat exchanger. First, we investigated the fan by comparing the total pressure efficiency when the fan was mounted in an indoor unit and unmounted as a standalone fan. We found that the mounted fan performed worse than the standalone fan. The difference between these conditions was whether the heat exchanger was around the fan. Next, to determine the appropriate diameter, the performance of the mounted fan was evaluated by measuring its efficiency and the fan power. The diameter with the highest efficiency differed from the diameter with the lowest fan power. Because of this, the fan performance was strongly affected by the heat exchanger and the vortex. When the standard deviation of the air flow distribution in the heat exchanger was evaluated, the diameter with the lowest standard deviation was the same as the diameter with the lowest fan power. Since the standard deviation needs to be reduced to improve the performance of both the fan and the heat exchange cycle, the mounting conditions need to be considered to determine the fan shape. Thus, the flow field around the fan was visualized, and the velocity distributions for the investigated diameters were compared. We found the distance between the fan and the heat exchanger was an important factor determining the performance. A fan with the most appropriate diameter was prototyped to evaluate the fan performance. Results revealed it used 3% less power than a standard-diameter fan.

Analysis of Flow Mal-Distribution in a Cross-Flow Heat Exchanger

2014 ◽  
Vol 592-594 ◽  
pp. 1428-1432 ◽  
Author(s):  
Krishna P. Mohan ◽  
Shekar M. Santosh ◽  
M. Ramakanth ◽  
M.R. Thansekhar ◽  
M. Venkatesan
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Cross Flow ◽  
Flow Distribution ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Uniform Flow Distribution ◽  
Flow Heat ◽  
Channel Assembly ◽  
Uniform Fluid

Flow mal-distribution is defined as the non-uniform fluid flow distribution among the parallel channels having a common header. Flow mal-distribution is present in every header channel assembly. This mal-distribution has a significant effect on the performance of the heat exchanger by increasing the pressure drop and affecting the heat transfer characteristics. However, in designing a heat exchanger, a uniform flow distribution in each channel is assumed. The present work attempts to reduce the flow mal-distribution in a cross flow heat exchanger. A numerical analysis is done using a commercial code ANSYS FLUENT 3D and the results are validated experimentally. A parametric study is done by changing the size of the channels within the heat exchanger so as to reduce the flow mal-distribution. The effect of varying channel size on flow mal-distribution and pressure drop across the heat exchanger is studied and a geometry with reduced flow mal-distribution is found.

scholarly journals Study on turbulent flow in wave wall tube heat exchanger

2021 ◽  
Vol 2076 (1) ◽  
pp. 012025
Author(s):  
Liang Zhang ◽  
Anlong Zhang
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Average Pressure ◽  
Flow State ◽  
Tube Heat Exchanger ◽  
Exchange Performance ◽  
Straight Wall ◽  
Corrugated Structure

Abstract The traditional straight wall tube heat exchanger has low heat exchange efficiency, in order to solve this problem, the turbulent flow in wave wall tube heat exchanger was studied by numerical simulation. It is found that the unique corrugated structure of the heat exchange tube in the wave wall tube heat exchanger can improve the flow state of the fluid in the heat exchanger. The average pressure drop of heat exchanger gradually increases with the increase of Reynolds number Re. Under the same conditions, the average pressure drop of wave wall tube heat exchanger is lower than that of straight wall tube heat exchanger. The improvement of heat exchange performance of heat exchanger can not be realized only by increasing the inlet flow of heat exchanger. The wave wall tube heat exchanger can strengthen the heat exchange of the fluid in the heat exchanger.

CFD Optimization of Gas-Side Flow Channel Configuration Inside a High Temperature Bayonet Tube Heat Exchanger With Inner and Outer Fins

2011 ◽  
Author(s):  
T. Ma ◽  
Y. P. Ji ◽  
M. Zeng ◽  
Q. W. Wang
Keyword(s):  
Reynolds Number ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Flow Distribution ◽  
Flow Channel ◽  
Original Design ◽  
Tube Heat Exchanger ◽  
Channel Configuration ◽  
Model C ◽  
Side Flow

In this paper, the gas-side fluid flow distribution inside a bayonet tube heat exchanger with inner and outer fins is numerically studied. The heat exchanger is designed based on the traditional bayonet tube heat exchanger, where compact continuous plain fins and wave-like fins are mounted on the outside and inside surfaces of outer tubes, respectively, to enhance the heat transfer performance. However, gross flow maldistribution and large vortices are observed in the gas-side flow channel of baseline design. In order to improve the flow uniformity, three modified designs are proposed. Three vertical plates and two inclined plates are mounted on the inlet manifold for Model B. For the Model C, another six bending plates are mounted on the middle manifolds and three pairs of them are connected together. The Model D has a similar structure as Model C except for the two additional baffles. The results indicate that the flow distributions of Model C and D are much more uniform under different inlet Reynolds number, especially in the high inlet Reynolds number. Although the flow distribution of Model D is the best, its pressure drop is 2.6 times higher than that of Model C. Therefore, the design of Model C is the most optimized structure. Compared with the original design, the nonuniformity of Model C can be reduced by 42% while the pressure drop is almost the same under the baseline condition.

scholarly journals Increasing the efficiency of split type air conditioners/heat pumps by using ventilating exhaust air

2019 ◽  
Vol 100 ◽  
pp. 00006 ◽  
Author(s):  
Wojciech Cepiński ◽  
Paweł Szałański
Keyword(s):  
Energy Efficiency ◽  
Heat Exchanger ◽  
Ventilation System ◽  
Electricity Consumption ◽  
Heat Pumps ◽  
Design Solution ◽  
Simple Design ◽  
Air Conditioner ◽  
Air Conditioners ◽  
Heat Demand

The article presents the possibility of using exhaust air from ventilation system to increase the efficiency (SCOP, COP, SEER and EER) of commonly used air conditioners with the function of a heat pump. These types of devices are very popular both in residential and in public buildings. The topic discussed in the article is very important, because the widespread increase of the energy efficiency of these devices significantly influences national electricity consumption. The possibility of increasing their efficiency by directing the exhaust air from the ventilation system to the heat exchanger of the air conditioner outdoor unit has been analysed. It has been shown that the use of the simple design solution described in the article allows for a significant increase of the efficiency of these devices (seasonal efficiency even up to 35% at 100% share of exhaust air), reducing the energy consumption and increasing their capacity and operation range. By increasing the share of exhaust air it is possible to ensure year-round operation of the device and even 100% coverage of heat demand.

Problems of the Heat Exchanger for Vehicular Gas Turbines

1976 ◽  
Author(s):  
E. Tiefenbacher
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Gas Turbine ◽  
Fuel Consumption ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
Flow Distribution ◽  
Short Review ◽  
Piston Engine

It is well known that a vehicular gas turbine needs a heat exchanger to compete in fuel consumption with the piston engine, especially with the diesel. A short review of the theory of heat exchange shows that very small hydraulic diameters must be used to obtain a reasonable heat exchanger volume. This causes a number of problems for the fabrication, engine configuration, flow distribution, etc. These problems are discussed in conjunction with experience gained during the development of a number of heat exchangers (1).

Study of High Efficiency and Low Noise Centrifugal Fan

2011 ◽  
Author(s):  
Takanori Nagae ◽  
Zhiming Zheng
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Low Noise ◽  
Leakage Flow ◽  
Pressure Side ◽  
Centrifugal Fan ◽  
Air Conditioner ◽  
Air Conditioners ◽  
Leakage Flows ◽  
Centrifugal Fans

Centrifugal fans are widely used for air-conditioning equipments. Demands for air conditioners have arisen for quiet considered the indoor condition, energy saving associated with the global warming, and which have made it important to develop high performance fans. In order to meet these demands, the technology was studied to reduce leakage flow for a high efficiency and low noise centrifugal fan in this research. Leakage flow occurs when a part of air discharged from fans flows into a gap between the bellmouth and the shroud. This flow is the pressure loss because it returns from the high-pressure side to the low-pressure side wastefully. Furthermore, the high noise is caused, because this leakage air can’t flow along the shroud. As the final successful technology to reduce leakage flow, we have developed for the new bellmouth with multiple ribs on the bellmouth plane placed opposite fan. By using the new bellmouth, the centrifugal fan’s motor input for the 4-direction ceiling-embedded cassette type air conditioner has been reduced by 5.4[%] and the noise by 1.2[dBA]. We analyzed the leakage flow structures of the centrifugal fan were analyzed by the numerical simulation and LDV measurements. It has been found that the leakage flow is decreased, since the partial leakage flows back in an opposite direction to a gap between the bellmouth and the shroud. Additionally, it has been found that the turbulence intensity of outlet airflow is decreased by the new bellmouth.

A Relation Between Two-Phase Pressure Drop and Flow Distribution in a Compact Heat Exchanger Header

2004 ◽  
Author(s):  
Jong-Soo Kim ◽  
Ki-Taek Lee ◽  
Jae-Hong Kim ◽  
Soo-Jung Ha ◽  
Yong-Bin Im
Keyword(s):  
Experimental Study ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Single Phase ◽  
Small Diameter ◽  
Flow Distribution ◽  
Compact Heat Exchanger ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Pressure

In this paper an experimental study was performed for relation between two-phase pressure drop and flow distribution in compact heat exchanger using small diameter tubes. We performed the experimental study in non-heating mode. A test section was consisted of the horizontal header (circular tube: φ 5 mm × 80 mm) and 10 upward circular channels (φ 1.5 mm × 850 mm) using acrylic tube. Three different types of tube insertion depth were tested for the mass flux and inlet quality ranging from of 50–200 kg/m2s and 0.1–0.3, respectively. Air and water were used as the test fluids. Two-phase pressure drop of each channel and three type of distribution header was measured. As whole, single-phase and two-phase, pressure drop in rear channel is found to be lower than that in front channel. In conclusion, we can claim that principle of distribution is almost same pressure drop in each channel. Comparing pressure drop in branch tube with correlation equation, it was found that in single-phase flow, experimental value was 10% lower than Hagen-Poiseuille, Blasius equation (Eq. 40) in two-phase flow.

Analysis of Internal Flow Field for Centrifugal Fan in Series

2012 ◽  
Vol 233 ◽  
pp. 96-99
Author(s):  
Ya Jun Fan ◽  
Zhang Xu ◽  
Ding Wensi
Keyword(s):  
Velocity Distribution ◽  
Total Pressure ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Wind Pressure ◽  
Meridian Plane ◽  
Centrifugal Fan ◽  
Fan Performance ◽  
In Series ◽  
The Impact

Centrifugal fan in series with high wind pressure is the key facility of pneumatic transport equipment. To consider the impact of changed conditions on performance of centrifugal fan, internal flow of three-stage centrifugal fan at rated speed in different total pressure conditions is analyzed by CFD software FLUENT6.3 in this paper. Flow characteristics are obtained and the differences of total pressure and velocity distribution in each impeller are analyzed under different conditions, velocity distribution on the meridian plane and section of wind guide plates are compared. Finally, curves of P-Q and P-η at 4600 r/min are forecasted through the analysis of the data, which provide references for reducing impact that condition alteration on fan performance and improving the efficiency of the fan.

scholarly journals NGNP Process Heat Utilization: Liquid Metal Phase Change Heat Exchanger

2008 ◽  
Author(s):  
Piyush Sabharwall ◽  
Mike Patterson ◽  
Vivek Utgikar ◽  
Fred Gunnerson
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Liquid Metal ◽  
Phase Change ◽  
Heat Exchangers ◽  
Liquid Metals ◽  
Compact Heat Exchangers ◽  
Process Heat

One key long-standing issue that must be overcome to fully realize the successful growth of nuclear power is to determine other benefits of nuclear energy apart from meeting the electricity demands. The Next Generation Nuclear Plant (NGNP) will most likely be producing electricity and heat for the production of hydrogen and/or oil retrieval from oil sands and oil shale to help in our national pursuit of energy independence. For nuclear process heat to be utilized, intermediate heat exchange is required to transfer heat from the NGNP to the hydrogen plant or oil recovery field in the most efficient way possible. Development of nuclear reactor-process heat technology has intensified the interest in liquid metals as heat transfer media because of their ideal transport properties. Liquid metal heat exchangers are not new in practical applications. An important rationale for considering liquid metals as the working fluid is because of the higher convective heat transfer coefficient. This explains the interest in liquid metals as coolant for intermediate heat exchange from NGNP. The production of electric power at higher efficiency via the Brayton Cycle, and hydrogen production, requires both heat at higher temperatures and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. Compact heat exchangers maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. High temperature IHX design requirements are governed in part by the allowable temperature drop between the outlet of NGNP and inlet of the process heat facility. In order to improve the characteristics of heat transfer, liquid metal phase change heat exchangers may be more effective and efficient. This paper explores the overall heat transfer characteristics and pressure drop of the phase change heat exchanger with Na as the heat exchanger coolant. In order to design a very efficient and effective heat exchanger one must optimize the design such that we have a high heat transfer and a lower pressure drop, but there is always a tradeoff between them. Based on NGNP operational parameters, a heat exchanger analysis with the sodium phase change is presented to show that the heat exchanger has the potential for highly effective heat transfer, within a small volume at reasonable cost.

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