Performance Evaluation and Optimization of a Refrigerant Distributor for Air Conditioner
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Refrigerant mal-distribution in a distributor located at the inlet of the heat exchanger used for air conditioning systems plays an important role in the heat exchanger performance. The distribution performance at the distributor is greatly affected by flow conditions as well as geometrical parameters of the distributor. To clarify the distribution characteristics, it is essential to know flow rates of both liquid and vapor state at every branch tube after distribution. In other word, the information of the quality and the flow rate at the every branch tube are required. Acquiring this information, however, requires quite complicate experimental setup so far. This paper proposes a quite simple test method, however, allowing to obtain the value of quality and the flow rate of the refrigerant at the every branch tube of the distributor by measuring pressure drop and heat transfer rate of the branch tubes after distribution. By using the proposed evaluation method, the optimization for the geometrical parameters of the distributor was conducted to reduce the refrigerant mal-distribution and an optimized distributor is suggested. It is confirmed that the optimized distributor greatly reduces the mal-distribution of the refrigerant over the every branch tube regardless of the flow conditions. Meanwhile, by the flow visualization in the distributor, it is observed that certain amount of liquid refrigerant is stayed and swaying unstably at the bottom of the distributor. It is supposed that the liquid refrigerant behavior in the distributor great affects the distribution performance.Keywords:
Distributor
Vapor quality
Distributor
Fluidization
Expansion ratio
Superficial velocity
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An experimental investigation on the flow boiling behaviors in a vertical rectangular micro-channel was conducted.The channel has dimensions of 0.54 mm×1.6 mm×330 mm(width×depth×length).The working fluid is deionized water.Experimental results reveal that the pressure drop increases with increasing mass flux and exit vapor quality.And the pressure drop is mainly contributed by friction part,while the influences of gravitation,acceleration and single phase flow on pressure drop are relatively small.Based on the experimental results,new frictional factor correlations for single phase flow are suggested.In addition,the experimental data of Tang(2007) and Hrnjak(2007) are well prediced by the new frictional factor correlations.
Vapor quality
Mass flux
Microchannel
Flow coefficient
Working fluid
Flow boiling
Friction Factor
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This paper report about the swirling fluidized bed (SFB) which is affected by the designs of perforated plate. The result of the flow simulation for the each distributor plate perforated, inclines and annular are produces by using the Solid Work Flow Simulation intuitive (CFD). The characteristic of the each design plate are different in their number of hole, diameter of hole, thickness of plate and diameter of plate in order to get the best result which respect to pressure drop. The performance of the SFB was assessed in term of pressure drop values, minimum fluidization velocity, Umf. Also the performance of the each plate are looked at their flow air pattern in fluidized bed, which are the more swirl pattern of air the more better in result. More importantly is the reduction pressure drop in the appropriate design in distributor plate. The good results in this study were produced by the annular plate which is able to produce a minimum pressure drop compared with the perforated and Incline plate. While the annular plate also shown the swirl of air pattern better than perforated and incline plate. Furthermore, to ensure better results in this study, the experiment shall be conducted so that the results of the experiment can be compared with the flow simulation results. Besides that, from the experiment also the results that produce have more actual compare with flow simulation result.
Distributor
Fluidization
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Experimental study of frictional pressure drop characteristics of R410A-oil mixture flow boiling inside a small smooth tube was performed to promote the application of R410A in the compact heat exchanger of air-conditioner.The outside and inside diameters of the test tube are 5 mm and 4.18 mm,respectively.The test results show that the frictional pressure drop of R410A initially increases with vapor quality and then decreases,presenting a local maximum in the vapor quality range between 0.7 and 0.8;the frictional pressure drop of R410A-oil mixture flow boiling in small tube increases with the increase of oil concentration,vapor quality and mass flux;the presence of oil enhances frictional pressure drop maximum by 80%～120% as the oil concentration increases from 0 to 5% at vapor quality of 0.9.The frictional pressure drop of R410A-oil mixture in 5 mm smooth tube is about 10%～50% higher than that in 7 mm smooth tube.A new correlation of frictional pressure drop was developed for R410A-oil mixture flow boiling inside 5 mm small smooth tube,and it can agree with 94% of the experiment data within deviation of ±20%,and the average deviation is 8.5%.
Vapor quality
Boiling point
Flow boiling
Mass flux
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Vapor quality
Mass flux
Boiling point
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When the particles were fluidized with gas in columns packed with open-end cylindrical screen packing, the lowest pressure drop of the gas distributor which was required for good fluidization was measured. This pressure drop is defined as the critical pressure drop for good fluidization. The critical pressure drop in a screen-packed fluidized bed is influenced by the minimum fluidized gas velocity, bed diameter and fraction of open area in the distributor plate. Empirical correlations for critical pressure drop in the packed fluidized bed were obtained.When the particles were fluidized with gas under different fractions of open area in the gas distributor, the critical pressure drop decreased until a constant value was reached. This constant critical pressure drop is defined as the terminal critical pressure drop for good fluidization.In this study, empirical correlations for critical pressure drop in these two regions were obtained. At the same time empirical correlation between the pressure drop of a perforated gas distributor and operating conditions was obtained.
Distributor
Fluidization
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Distributor
Fluidization
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The pressure drop across the distributor signifies the total pressure drop and ensures desired fluidization in the fluidized bed. This study estimates the pressure drop requirements for 1.2 and 2.05 mm particles utilizing two distinct perforated type conical distributors with 154 and 302 orifices, respectively. The investigation was carried out in a cold flow condition. The pressure drop across the distributor was introduced in this investigation by filling bed material in the conical portion of the distributor. To estimate the bed pressure, a combined pressure drop of the conical distributor with and without bed material was approached. Explicitly, pressure drop requirements for the minimum fluidization and bubbling regimes have been focused on and presented in this work. In view of bed pressure, an attempt has been made to establish a relationship for pressure requirements across distributors. The integration and estimation of pressure drop across distributor with bed material in conical portion could be very beneficial in view of the fluidized bed. As the bed height increased, the pressure increased, but the pressure drop ratio decreased for the selected particles. The distributor features a higher number of orifices that demonstrate lower pressure requirements during fluidization and bubbling regimes. This study emphasizes the desired pressure requirements for the fluidized bed.
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Distributor
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Abstract Experiments were carried out to examine the influence of both the type and the pressure drop of distributor plates on the fluidization quality of an atmospheric fluidized bed. Three different distributor types were used, perforated Perspex, metallic mesh, and porous ceramic, with pressure drops ranging from 0.05 to 350 kPa and superficial air velocities ranging from 0.1 to 2.3 m/s. Three sizes of silica Ballotini beads, 355–425, 600–710, and 850–1000 µm, were used as bed material. The static bed height was set to 300 mm and was divided into six horizontal 50 mm high slices. For each slice, pressure drop values were recorded for U0/Umf ratios from 20 to 1. In order to produce a reference for the pressure drop evolution, a modification of the two-phase theory was introduced, taking into consideration the increase in the average global porosity as well as the change in the ratio of flow through the bubbles versus the flow through the dense phase. This allowed assessment of the influence of the different operating conditions and setups on the quality of fluidization, Q∗. Keywords: Distributor plateFluidizationQualityPressure drop
Fluidization
Distributor
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In this paper, a fluidized bed with a adjustable slotted gas distributor was used to study fluidization in a 230 mm×200 mm rectangular fluidized bed by adjusting the spacing between the two slotted gas distributors. The pressure drop of the distributor at different inlet gas velocities was obtained and the change law between pressure drop and distance between distributors was summarized. This study provides a theoretical basis for the application of adjustable slotted gas distributor fluidized bed.Keywords: Geldart D; Adjustable slotted gas distributor; Pressure drop
Distributor
Fluidization
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