Many people are pretty happy with their scraped-surface heat exchangers, but Erich Windhab is not one of them. A tall, cheerful German with a beard, longish hair, and a shiny suit, he does not believe in complacent adherence to tradition. There is no denying the lingering appeal of scraped-surface heat exchangers, particularly at large family gatherings on hot summer days, but Windhab is not sentimental about their output. He likes the stuff his graduate students make better. “When Hans and Matthias are producing, everybody at the Technopark lines up with bowls,” he says.
A scraped-surface heat exchanger is what someone with a Ph.D. in chemical engineering calls an ice-cream freezer. At giant food companies like Nestlé or Unilever but also at university labs like Windhab’s—he’s a professor at the Federal Institute of Technology in Zürich, Einstein’s old shop—there are many Ph.D.’s consumed by the science of ice cream. “People laugh when I tell them,” says Hans Wildmoser, who just completed his degree under Windhab. And yet ice cream, of course, is serious business: Sales of frozen desserts, most of which are ice cream, total about $20 billion and 1.5 billion gallons a year in the United States alone. Americans consume more than 20 quarts per capita every year, second only to New Zealanders.
