Transient Characteristics of Split Air-Conditioning Systems Using R-22 and R-410A as Refrigerants

Kapadia, Ragesh G.; Jain, Sanjeev; Agarwal, Radhika

doi:10.1080/10789669.2009.10390854

Cited by 33 publications

(2 citation statements)

References 37 publications

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“…The local heat transfer coefficient of the herringbone grooved tube was better than that of the spiral tube under either condensation or evaporation conditions. In 2009, Kapadia et al 3 used R22 and R410A to study the transient characteristics of an independent air conditioning system, and found that the total transient loss ratio of the R410A system was 18.5%, while the transient loss ratio of the R22 system was 18.7%. Under the same working conditions, the R410A system has a lower transient loss because of refrigerant migration.…”

Section: Introductionmentioning

confidence: 99%

Experimental comparison on condensation and evaporation outside double-side enhanced horizontal tubes

Cheng

Lei

Huang

et al. 2022

Advances in Mechanical Engineering

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Experimental investigations of the condensation and evaporation of R410A on the outside of two double-side enhanced heat transfer tubes were conducted, and the tube performance was compared with that of a smooth copper tube. The research object consisted of a smooth tube with a length of 2000 mm and an outer diameter of 25.4 mm and two double-side enhanced tubes of the same size. The evaporation experiments were run under the following conditions: the evaporation saturation temperature was 7°C, water inlet temperature was 8°C–18°C, and water flow rate was 0.6–1.6 m3/h. The condensation experiments were run under the following conditions: the saturation temperature was 35°C, water inlet temperature was 21°C–30°C, and water flow rate was 0.4–1.6 m3/h. During the data processing, the heat transfer coefficient of the water side was obtained using the Gnielinski-Wilson method, and that of the refrigerant side was obtained using the thermal resistance separation method. The effect of the surface structure on the heat transfer performance was analyzed, and a strengthening measure was proposed. The experimental results indicate that the evaporation heat transfer coefficients outside the smooth tube increased with the raise of the inlet water temperature, while the double-side enhanced tubes decreased; both the condensation heat transfer coefficients outside the smooth tube and the enhanced tubes increased with the increase of the water flow rate. Due to the different type of enhanced tube ribs, tube #3 surface structure is more conducive to the formation of vaporization core, which is about 30% higher than the outer heat transfer coefficient of tube #2. It is more in line with the requirements of strengthening horizontal single tube external pool boiling heat transfer. In the condensation experiment, the condensation heat transfer coefficients outside the smooth tube increased with the raise of the inlet water temperature, while the double enhanced tubes decreased; both the condensation heat transfer coefficients outside the smooth tube and the enhanced tubes increased with the increase of the water flow rate. With the analysis of the rib structure, the outer surface structure of tube #2 has stronger drainage capacity, and the external average condensation heat transfer coefficient is about 7% higher than that of tube #3, which is more in line with the requirements of condensing heat transfer outside the single tube.

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Section: Introductionmentioning

confidence: 99%

Experimental comparison on condensation and evaporation outside double-side enhanced horizontal tubes

Cheng

Lei

Huang

et al. 2022

Advances in Mechanical Engineering

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show abstract

“…A natural extension of the MB approach is the nite control volume method that utilizes a larger number of control volumes to capture system dynamic characteristics at a higher granularity and thus, o ers improved model accuracy. Kapadia et al (2009) presented anite control volume model of DX air conditioning systems to predict system transient characteristics during system startup. Beghi and Cecchinato (2009) used a similar nite control volume model to assist design of an auto-tuned PID controller for EXV, where actuation constraints such as upper bound and hysteresis were accounted for explicitly.…”

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confidence: 99%