Introduction to How Grills Work
Outdoor grilling is a very popular method of cooking. In fact, approximately 75 percent of U.S. households have a grill. A grill consists of a cooking surface, typically made of parallel metal bars or a porcelain-covered metal grid, over a fuel source capable of generating intense heat, usually up to temperatures of 500 degrees Fahrenheit (260 C) or more.
There are several different types of grills, but gas and charcoal are by far the most common.
In this article, you will learn about the parts of a grill and how they work together. You'll learn what charcoal is and how it is made, as well as about the differences between liquid-propane (LP) and natural-gas grills. You'll also find out about other less-common types of grills and their fuel sources.
Let's start by taking apart the trusty charcoal grill.
The components of a grill can range from very simple to incredibly sophisticated. The simplest grill is a charcoal burner and has three components:
- Cooking surface
- Charcoal container
- Grill support
A common version of this arrangement uses a shallow, round container mounted on a metal tripod, with a round cooking grill that rests on top of the container. Look at the example below:
Charcoal grills can be more complex than this -- some have a hood to cover the grill and additional tiered cooking surfaces -- but the basics are the same.
The fuel source for charcoal grills has been around for at least 5,000 years. No one is certain who discovered charcoal or even what civilization first used it. Evidence of charcoal has been found all over the world. It was even used in the embalming process for Egyptian mummies!
You may not realize it, but charcoal is not a rock or even some type of coal. It is actually wood! Charcoal is created by heating wood to high temperatures in the absence of oxygen. That is, you take wood, put it in a sealed box of steel or clay and heat it to about 1000 F (538 C).
Why would you go through such a tedious process instead of just burning the wood as it is? Freshly cut wood contains a lot of water -- sometimes more than half its weight is water. Seasoned wood (wood that has been allowed to sit for a year or two) or kiln-dried wood contains a lot less water, but it still contains some. Watery wood does not make for very efficient cooking. Also, when the tree was alive it contained sap and a wide variety of volatile hydrocarbons in its cells. "Volatile" means that these compounds evaporate when heated.
When you put a fresh piece of wood or paper on a hot fire, the smoke you see is those volatile hydrocarbons evaporating from the wood. They start vaporizing at a temperature of about 300 F (149 C). If the temperature gets high enough, these compounds burst into flame. Once they start burning, there is no smoke because the hydrocarbons turn into carbon dioxide and water vapor (both invisible).
This explains why you see no smoke from a charcoal fire (or a fire that has burned down to embers). This process drives off all of the volatile organic compounds and leaves behind pure carbon and ash (the non-burnable minerals in the tree's cells). When you light the charcoal, what is burning is the pure carbon. It combines with oxygen to produce carbon dioxide, and what is left at the end of the fire is the ash -- the minerals. This produces a very intense heat with very little smoke, making charcoal very useful as a cooking fuel that will not overwhelm the flavor of the food with the elements found in normal wood smoke.
Grilling enthusiasts passionately argue the merits of charcoal versus gas grilling, citing especially the difference in flavor. Charcoal does provide a distinctive flavor that is not easily reproduced. It is a tough decision for many people: the convenience of a gas grill against the flavor of charcoal. Let's take a look at gas grills and how they work.