Transportation Tip
A Portable, Inexpensive, Farm-Built, Precooler
From the time of harvest, fruits and vegetables begin a natural decline in quality. When a product is harvested, field heat—the heat that the product holds from the sun and outside temperature—is usually high, which results in an increased rate of respiration and greater deterioration, This decrease in quality cannot be prevented, but can be slowed by rapid temperature reduction or precooling soon after harvesting.
Farmers and marketers can protect their harvested fruits and vegetables, such as berries and other high-value crops, by building and using their own portable precooler. The Portacooler can easily be utilized by small farmers and roadside marketers.
The design of the Portacooler is simple. It can be built with tools commonly found in most workshops. A hammer, drill, screwdriver, circular saw, and a few other construction essentials are the only tools needed for the project. Most of the materials can be found around the farm, bought from a local hardware store, or purchased from an equipment catalog. A general list of the materials is on page 4.
The material cost for construction should be around $1,200 (July 1993 prices). Since an air conditioner is the most expensive component, a used air conditioner will greatly decrease the $1,200 initial investment. The initial cost can be expected to be recovered through increased sales and profits from a higher quality product that has a longer shelf life.
The structure of the Portacooler is a basic wood frame and plywood panel construction (see diagram on inside pages). The outside dimensions of the cooler are 4 feet high by 4 feet wide by 8 feet long. The frame is made of 2 by 3’s spaced 2 feet on center, excluding the doorway and the air conditioner space. The frames are sheathed with 1/4-inch plywood. The frame and sheathing are fastened using 2 1/2-inch and 1-inch dry wall screws, respectively. Insulate the precooler with 2-inch-thick plastic foam that fits firmly between the frame studs.
After the frame and sheathing steps are completed, install the electrical components (see diagram on page 4). The standard junction box, power switches, daily cycle timer, and industrial thermostat control box should be mounted on the outside of the front wall near the air conditioner, An adjustable, industrial thermostat must be connected to the air conditioner to replace the existing thermostat. Mount strip heaters using copper wire so that they contact the cooling coils of the air conditioner. Mount the blower on the front inside wall, centered above the air conditioner so that the blower discharge is 12 inches below the inside ceiling.
