(150a) Experimental Investigation of Heat Transfer and Pressure Drop in Pillow-Plate Condensers

Pillow-plate condensers represent technologically advanced heat exchangers. They have a compact, light and fully hermetical construction as well as excellent heat transfer characteristics, which brings about low capital and overall operating costs. However, the implementation of pillow-plate condensers in process industries is still limited, because their reliable design methods are largely missing, while only basic studies are available in the literature [1,2]. Extensive experimental and numerical investigations of our group have recently been carried out to overcome this limitation [3,4].

Two different experimental set-ups were used to determine thermohydraulic properties of pillow-plate condensers. The first set-up was applied to study the flow and heat transfer in inner channels of pillow plates, through which pure water and monoethylene glycol/water mixtures were pumped. For different types of pillow plates and for a wide range of operating conditions, specific pressure drop and heat transfer coefficients were determined.

Another experimental set-up was used to analyze the condensation of water and isopropyl alcohol in a pillow-plate heat exchanger in presence of a non-condensable component. With this second set-up, results for two-phase pressure drop and overall heat transfer coefficients were obtained. Having determined both the overall and the inner-side heat transfer coefficients, we were able to calculate also the heat transfer coefficients on the outer condensation side.

In this contribution, the key findings of the experimental investigations are outlined. The experimental data were represented in a compact, dimensionless form and implemented in a Visual Basic programming environment, which allowed local determination of the fluid properties, pressure drop and heat transfer coefficients along the heat exchanger, both on the inner cooling medium side and on the outer condensation side. The resulting software tool was subsequently used for simulation studies and for a comparison of the calculated pressure drop and heat transfer coefficients with our own experimental data and with literature values obtained with conventional heat exchanger types.

The outcomes of this work will help to facilitate application of pillow-plate condensers and, consequently, to improve the overall energy efficiency in process industries.

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