When I saw that Robin had written a blog about a beer fridge I thought he had beaten me to the punch. In my spare time I too have been using our CFD tools to analyze a beer fridge. The differences are I am using FloVENT and my fridge is a self-service refrigerated showcase. The story of the showcase is not complete but I want to provide the first installment.
The idea of the open (self-service) refrigerated showcase interests me as a thermal/airflow designer and as a consumer. I certainly like standing in front of a showcase without having to contend with an obtrusive door. Invariably though, while I am weighing the beverage options, I think about the design of the refrigerator.
I would like to believe that a “jet” of air from the top of the unit will provide a curtain between me and the beverage. It has been my experience that though you can sketch the flow path on a napkin that you desire air doesn’t always know where you had intended it to go. How much of that curtain is reaching it’s destination to be re-chilled? How much of it enters the aisle? Does it cause discomfort to the consumer?
To begin to understand the airflow path I built a representative FloVENT CFD model. My display has two supplies at the top, the outer supplies air at about 1.5 ft/sec and the inner at half of the outer. I wanted to pick some very low airflow speed that is essentially undetectable by a human, because I never feel any air movement in these “curtains”. The two streams of air, where only the inner stream is re-chilled, are imagined to travel to the returns near the bottom of the display. To show the air flow path I have uploaded an animation shown below, where the particles are colored by temperature.
To my delight it appears that even a curtain at a very low flow speed provides a reasonable barrier to the customer. For further understanding I seeded the inner and outer supplies so we could quantitatively determine the effectiveness of the curtain. The contour plots below are colored by the flow markers for the inner and outer flows. A value of 1 indicates 100% flow from the associated supply.
The initial analysis shows that the chilled air is contained pretty well but some of the un-chilled air does enter our display. The next step will be to vary some of the flow and design parameters and perform a Response Surface Optimization to determine what variables influence the performance the most.