A COMPARATIVE STUDY ON THE PERFORMANCE OF THE DOMESTIC REFRIGERATOR USING R600A AND LPG WITH VARYING REFRIGERANT CHARGE AND CAPILLARY TUBE LENGTH

2017 ◽  
Vol 18 (4) ◽  
pp. 287-302 ◽  
Author(s):  
Sunday O. Oyedepo ◽  
R. O. Fagbenle ◽  
Taiwo O. Babarinde ◽  
K. M. Odunfa ◽  
R. O. Leramo ◽  
...  
Keyword(s):  
Comparative Study ◽  
Capillary Tube ◽  
Tube Length ◽  
Domestic Refrigerator

Comparative Study on a Straight and Helical Capillary Tube for CO2 and R22 Refrigerant

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Pravin Jadhav ◽  
Neeraj Agrawal
Keyword(s):  
Numerical Model ◽  
Comparative Study ◽  
Capillary Tube ◽  
Tube Diameter ◽  
Tube Length ◽  
Percentage Reduction ◽  
Basic Principles ◽  
Conservation Of Mass ◽  
Coil Diameter ◽  
Mass Flowrate

Abstract A comparative study has been carried out on the adiabatic straight and helical capillary tube, using a CO2 and R22 refrigerant. The numerical model for CO2 and R22 is developed using the basic principles of conservation of mass, momentum, and energy. The effect of coiling in the helical capillary tube is compared with a straight capillary tube for CO2 and R22 refrigerant. Compared with the straight capillary tube, the percentage reduction in mass flowrate in the helical capillary tube is calculated with a change in coil diameter, tube diameter, and length. As the coil diameter increases from 30 mm to 150 mm, the percentage reduction in mass is from 5.8% to 2.2% in CO2, and 5% to 1.6% in R22. For helical capillary tube with 50 mm coil diameter, as the tube diameter increases from 1 to 1.5 mm, the percentage reduction in mass flowrate with CO2 refrigerant is from 2.65% to 4.96%, however, for R22 it is from 2.43% to 4.24%. Similarly, as the capillary tube length increases from 1.3 m to 1.8 m, the percentage reduction in mass with CO2, with 50 mm coil diameter is 4.44–4.55%. However, the percentage reduction in mass with R22 is 3.71–3.85%. Moreover, compared with the straight capillary tube, the percentage reduction in length in a helical capillary tube with coil diameter 50 mm is 16% for CO2 and 9% for R22 refrigerant.

Experimental Investigation on Flow Characteristic of Stepped Capillary Tube for Heat Pump Type Air Conditioner with R410A

2014 ◽  
Vol 960-961 ◽  
pp. 643-647
Author(s):  
Yan Sheng Xu
Keyword(s):  
Mass Flow Rate ◽  
Heat Pump ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Coefficient Of Performance ◽  
Tube Length ◽  
Air Conditioner ◽  
Capillary Tubes ◽  
Tube Assembly

A stepped capillary tube consisting of two serially connected capillary tubes with different diameters is invented to replace the conventional expansion device. The mass flow rate of refrigerant R410A in stepped capillary tubes with different size were tested. The model of stepped capillary tube is proposed, and its numerical algorithm for tube length and mass flow rate is developed. The experimental results show that the performance comparing between stepped capillary tube system and capillary tube assembly system, the cooling capacity is reduced by 0.3%, the energy efficiency ratio (EER) is equal to each other, the heating capacity is increased by 0.3%, the coefficient of performance (COP) is decreased by 0.3%. That is to say, the performance index of the two kinds of throttle mechanism is almost identical. It indicates that the stepped capillary tube can replace the capillary tube assembly in the R410A heat pump type air conditioner absolutely. The model is validated with experimental data, and the results show that the model can be used for sizing and rating stepped capillary tube.

Abstract P211: N-Acetyl-Seryl-Aspartyl-Lysyl-Proline (Ac-SDKP) Promotes Tube Formation in Human Coronary Artery Endothelial Cells

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Ginette Bordcoch ◽  
Pablo Nakagawa ◽  
Cesar A Romero ◽  
Oscar A Romero
Keyword(s):  
Endothelial Cells ◽  
Coronary Artery ◽  
Capillary Tube ◽  
Tube Formation ◽  
Endothelial Cell Migration ◽  
Tube Length ◽  
Human Coronary Artery ◽  
Double Phase ◽  
Angiogenic Effect

Ac-SDKP is an endogenous peptide with anti-inflammation and anti-fibrotic effects in hypertensive and cardiovascular diseases. It is cleaved from Thymosin β4 (Tβ4) and hydrolyzed by angiotensin converting enzyme (ACE). Ac-SDKP plasma concentration increases after treatment with ACE inhibitors (ACEi) and some of the beneficial effects of ACEi treatment has been ascribed to Ac-SDKP. Ac-SDKP is a mediator of angiogenesis in in-vitro and in-vivo animal models. Ac-SDKP stimulates rodents derived immortalized aortic endothelial cells migration and capillary-like structures formation (tube formation). Similarly, Ac-SDKP increases capillary density after myocardial infarction in rats. The mechanism related to angiogenesis induced by Ac-SDKP is not known. Tβ4 (Ac-SDKP precursor) promotes endothelial cell migration and angiogenesis by the activation of the VEGF/AKT pathway. Our objective is to evaluate the Ac-SDKP pro-angiogenic effect in Human Coronary Artery Endothelial Cells (HCAEC) and the mechanism that regulates the angiogenic effect of Ac-SDKP. HCAEC do not produce VEGF, thus we hypothesize that Ac-SDKP increases VEGF expression in fibroblasts and that indirectly could promote capillary tube formation in endothelial cells. We used primary culture of rat cardiac fibroblast (RCF) and we treated these cells with 10nM Ac-SDKP for 24 hours. VEGF concentration in cell supernatant was measured by ELISA. Cells were starved without serum overnight before the Ac-SDKP treatment. For capillary tube formation assay, HCAEC cells were seeded into matrigel and incubated in presence of 10nM Ac-SDKP for 12 hours, pictures were taken by double phase contrast microscope and tube length was quantified with image J software and the results were expressed as percentage of control. After Ac-SDKP treatment, VEGF concentration did not increase in the supernatant of RCF (control: 0.12±0.07 vs. Ac-SDKP: 0.14±0.09 mg/ml; p=0.7). However, Ac-SDKP treatment induced the development of tube formation in HCAECs by 7±2% respect to control (p=0.037). We conclude that Ac-SDKP induces capillary tube formation not only in rodent but also in human derived endothelial cells. The mechanism by which Ac-SDKP promotes tube formation in HCAECs is still unknown.

scholarly journals Comparative study on destructive performance and energy absorption of aluminum tube by simulation and experiment

2020 ◽  
Vol 12 (5) ◽  
pp. 168781402092413
Author(s):  
Lai Hu ◽  
Jun Zha ◽  
Yaolong Chen
Keyword(s):  
Comparative Study ◽  
Energy Absorption ◽  
Simulation Analysis ◽  
High Energy ◽  
Low Energy ◽  
Tube Length ◽  
Thin Wall ◽  
Span Length ◽  
Aluminum Tube ◽  
High Energy Absorption

This study conducted an investigation on transverse quasi-static three-point loading on a circular aluminum tube and its characteristic plastic failure and energy-absorption behaviors. The thin wall thickness of the aluminum tube, the various diameter and thickness ratios ( D/ t) of the tube, and the tube length are important control parameters. Experimental data for different span length and thickness ratios of the tube were characterized and correlated to its plastic collapse behavior. A simulation model by computational analysis using ANSYS was also conducted as a comparative study. The results of the study found that transverse three-point bend loading (ASTM F290) of a circular aluminum tube underwent different stages of deformation, from initial pure crumpling to crumpling and bending, and finally, structural rupture. The results of master curve analysis found that regions of high energy absorption and low energy absorption can be classified with respect to the characteristic tubular deformation. High energy absorption deformation is correlated with a short span length and higher D/ t ratio, and vice versa for low energy absorption deformation of the circular aluminum tube. Simulation analysis also predicted similar characteristic trends of deformation behavior in the experiment, with a less than 3% average coefficient of variation.

scholarly journals Investigation of Household Refrigerator System with Varied Capillary Tube Length

2019 ◽  
Vol 1378 ◽  
pp. 042056
Author(s):  
D. M. Madyira ◽  
G.T. Marangwanda ◽  
F.M. Ekundayo ◽  
T. O. Babarinde ◽  
S.A. Akinlabi
Keyword(s):  
Capillary Tube ◽  
Tube Length

General Equation for the Design of Capillary Tubes

1996 ◽  
Vol 118 (1) ◽  
pp. 150-154 ◽  
Author(s):  
Tuncay Yilmaz ◽  
Saban U¨nal
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
General Equation ◽  
Capillary Tube ◽  
Analytical Equation ◽  
Tube Length ◽  
Capillary Tubes

Capillary tubes are used widely in small refrigeration systems. It is necessary to design the capillary tube, but there does not exist any analytical equation which allows the determination of capillary tube length or mass flow rate for all refrigerants. In this work, an analytical equation is derived which allows to design the capillary tubes. The comparison with existing methods and experimentally obtained values using the refrigerants R12, R22, R113, R114, R134a, and R600a has turned out to be satisfactory.

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