Why Separate
The separation of the range and the fridge in a kitchen serves a couple of purposes. One reason for separation between appliances is to provide counter space for both the range and the refrigerator, so that when food is pulled from one you have a place to put it without having to move around the kitchen. Another reason to separate appliances in the kitchen is to ensure that the doors of those appliances do not get in the way of each other.
Operational Reasons
The range and the refrigerator are two of the biggest energy-sappers in your kitchen, with the refrigerator being the largest energy-user of the two because it runs constantly. Since the temperatures of a refrigerator and range are in contrast to each other, being in close proximity makes it more difficult for a range to heat and more difficult for the refrigerator to cool when the range is on.
Best Distance
Though no specific distance between appliances has been determined to be ideal spacing for maneuverability throughout the kitchen, keeping appliances within a few steps of each other can speed the process of food preparation and cleanup. Marilyn W. Caselman and Lelland L. Gallup of the University of Missouri recommend a distance between 4 and 9 feet between a range and a refrigerator. This spacing keeps the appliances far enough apart to keep them from interfering with each other but still close enough for food preparation.
Food Prep
If you have the opportunity to create your own kitchen layout, use your personal cooking style to determine the placement of each appliance. If you do a lot of baking or cooking from scratch, for instance, long stretches of counter space can be useful for kneading and rolling out dough. To get this length of counter space, you may need to place the appliances at either end of the counter, so that you don't have to break up the space.