The Intertube Falling-Film Modes: Transition, Hysteresis, and Effects on Heat Transfer

Siambekos, C.T.

Permalink

https://hdl.handle.net/2142/9694 Copy

Description

Title

The Intertube Falling-Film Modes: Transition, Hysteresis, and Effects on Heat Transfer

Author(s)

Siambekos, C.T.

Contributor(s)

Crawford, R.R.

Issue Date

1991-10

Keyword(s)

• plate-fin evaporator
• mobile air conditioning systems

Abstract

"The objective of the CU1TeJ1t study was to simulate the steady-state performance of an automotive air conditioning plate-fin evaporator. A one-zone model was defined for conditions when the evaporator outlet refrigerant exited as a two-phase mixture. A two-zone model was defined for conditions when the evaporator outlet refrigerant exited in a sUperheated state. An intermediate state was defined where the refrigerant changes from a saturated to a superheated vapor. 'Ibis intermediate state devided the evaporator into an evaporating and superheating section (Le. a two-zone model). The models were based on basic refrigerant momentum equations, air-side enthalpy potential equations, and air-side mass transfer equations. Each of these equations were applied to each section of the models. In order to predict the surface temperature, a refrigerant-side thermal resistance was defined thus allowing the surface temperature to ""float"" between the air and refrigerant temperatures. Furthermore, the predicted surface temperature was used for calculations in the enthalpy potential and the mass transfer equations. Embedded into each equation are parameters which are specific to both the heat exchanger geometry and the two working fluids (air and R-134a). Correlations for each of these parameters were determined with a least-squares fit of experimental data. Equation forms for the correlations developed were based on correlations found in the literature. It was found that the one- and two-zone models were able to predict the evaporator energy transfer, refrigerant pressure drop, air humidity ratio change, and air temperature change within a small percentage of the measured values. Finally, it was found that the trends for the model correlations developed described the parameters well."

Publisher

Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.

Series/Report Name or Number

Air Conditioning and Refrigeration Center TR-05

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/9694

Sponsor(s)/Grant Number(s)

Air Conditioning and Refrigeration Center Project 09

Owning Collections