Low Profile Design Air Tunnel System for a Refractance Window Dryer Taking the Weather Out of Food Drying

This patent describes an air tunnel that feeds conditioned air evenly across an industrial food drying) belt, so that a dryer performs the same way in Mildura in February as it does in a cold, damp July. It comes from E. & J. Gallo Winery, the Californian wine producer, which also processes large volumes of grape products.

The Problem

Refractance window drying is a gentle way of turning purees and juices into powders or flakes. A thin layer of liquid is spread onto a polymer belt that floats on hot water, and heat passes by conduction from the water, through the belt, into the product. Because the product itself never gets as hot as in conventional drying, colour, flavour and nutrients survive better.

The weak point is the air. Traditional systems flood the dryer with a large volume of ordinary ambient air to carry away the water vapour coming off the product. That means the humidity and temperature inside the dryer are effectively set by the weather outside. A dryer in a dry climate behaves differently from the same dryer in a humid one, performance shifts between summer and winter, and it can even change between day and night at a single site. Uncontrolled air also fails to do two things that would help: it does not actively raise the air temperature inside the dryer, and it does not lower the humidity, both of which increase how fast moisture leaves the product.

What This Invention Does

The system replaces the flood of ambient air with a managed supply. A conditioned air supply manifold delivers air of controlled temperature and humidity into the drying chamber, and the tunnel is designed with a low profile so that the airflow arrives uniformly along the belt rather than in hot and cold patches. A drying belt runs through the chamber, and a feed application tray at the first end of the belt applies the liquid product. An exhaust manifold sits at that same first end of the belt, so moisture-laden air is drawn away from the wettest part of the process, where evaporation is heaviest.

The result is a dryer whose internal conditions are set by the equipment rather than by the local climate. Conditioning the incoming air lowers its humidity, which increases the vapour pressure gradient pulling water out of the product, and holding the air uniform along the belt means the product at one edge dries at the same rate as the product at the other. That uniformity is what determines whether a run yields a consistent moisture content or a mix of scorched and underdried material.

Key Features

• Conditioned air supply manifold. Air of controlled temperature and humidity is supplied into the drying chamber instead of raw ambient air.
• Low profile air tunnel. The tunnel geometry delivers uniform air flow across the width and length of the drying belt.
• Feed application tray. A tray at the first end of the belt applies the liquid product in a controlled layer.
• End-located exhaust manifold. The exhaust manifold sits at the first end of the belt, removing vapour where evaporation is greatest.
• Climate independence. Because internal conditions are managed, dryer performance no longer varies with season, weather or time of day.

Who Is Behind It

The applicant is E. & J. Gallo Winery of Modesto, California, founded in 1933 and the largest family-owned winery in the United States. Beyond wine, the business handles large volumes of grape and fruit processing, which is where industrial drying equipment of this kind fits. The named inventors are Jorge Ortiz, Ernesto Rios Delao and Dan Burgess. The application is a divisional of Australian application 2023274248 and traces to an international filing, PCT/US2019/058055, with priority from October 2018.

Why It Matters

Drying is one of the most energy-hungry steps in food manufacturing, and inconsistent drying is a direct source of waste, since underdried product spoils and overdried product loses quality. Australian food processors run the same equipment across a continent with wildly different humidity, from tropical Queensland to dry inland horticultural regions, so a design that removes the climate variable has practical value here. Gentle drying methods also matter commercially because they preserve the colour and flavour compounds that let a powdered ingredient command a premium over a heat-damaged one.

Related Concepts

• Drying of food) – the preservation process this equipment performs.
• Evaporation – the physics the conditioned air is manipulating.
• Humidity – the variable that previously made dryer performance climate-dependent.
• Food processing – the wider industry this equipment serves.
• Heat exchanger – the equipment class used to condition the incoming air.
• Food dehydrator – the domestic-scale cousin of this industrial system.

---

AU 2026202028 was published in the Australian Official Journal of Patents on 2 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.