Ceramic infrared heaters create the opportunity to perform processes using noncontact heating. To those most familiar with conductive heating, it might appear that infrared radiation heating adds a few pages to the playbook. Advances in ceramic infrared technology and material selection have improved heater life and energy efficiency; however, build quality of the heaters greatly affects performance and heater life. This article will discuss the ways in which infrared heating technology can improve process efficiency and promote electricity savings in process heating applications.
Naturally occurring radiation was first discovered by astronomer and engineer Friedrich Wilhelm Herschel in 1800. Ceramic infrared heaters employed in industrial, health, livestock and other applications today can be traced to the Elstein-Werk Co.’s invention of the ceramic infrared heater technology in 1949 and 1950. While many ceramic infrared heaters in use today resemble those early heaters, advances in ceramic infrared noncontact heaters improve efficiency, throughput and heater life.
Infrared radiation is essentially a range of wavelengths that comprise a subset of the electromagnetic spectrum. The electromagnetic spectrum includes:
- Gamma radiation.
- X-ray radiation.
- Ultraviolet (UV) radiation.
- Infrared radiation.
Infrared wavelengths occur in the spectral 0.7 to 80 µm. Industrial ceramic infrared radiators generally use wavelengths between 2 and 10 µm.
Infrared wavelengths are absorbed as heat into materials. Materials absorb infrared energy at different rates. The absorption rate is a factor of material type, color, emissivity (reflection of infrared waves) and other factors. The infrared spectrum from the sun is responsible for heating the Earth. Similar to the way a concrete sidewalk is noticeably cooler than the adjacent asphalt under the same sun exposure, the absorption rate of process materials is an important consideration in the effectiveness of infrared technology.
Flat vs. Curved Ceramic Infrared Heaters
A large number of the ceramic infrared panel heaters sold today have a curved radiating surface. Originally, the curved surface was selected due to the manufacturing methods, desired uniformity from heater to heater, and product yields possible with the available equipment when the infrared heating technology was introduced in 1952. Modern ceramic infrared heaters with flat surfaces have highly similar radiation patterns and allow for a more compact installation. Many innovations associated with ceramic infrared panel technology have been introduced with the flat radiation surface.
Energy consumption has been an increasing global concern. Although the United States generally experiences lower electricity costs than most of the world, process electricity consumption is of growing concern, which has led to the development of energy-saving infrared heaters.
Energy-saving infrared heaters can have an impact on the bottom line of thermoforming companies, which typically have several machines with arrays of panel infrared heaters — from hundreds of heaters in smaller systems to thousands of heaters in larger systems. Thermoforming systems will often be among the largest power draws in a plant, affecting peak usage rates. Energy-saving infrared heaters incorporate insulation into the ceramic body of the system, directing more energy toward the heated surface and resulting in less dissipated energy away from the process.
Although energy-saving ceramic infrared heaters offer benefits to the end user of equipment, currently few OEMs offer them as an option. Over the life of a ceramic infrared heater, energy usage in dollars will be many multiples of the purchase price of the insulated heater. Energy-saving ceramic infrared heaters provide an opportunity to reduce operational costs.
The Future of Ceramic Infrared Heating Technology
Ceramic infrared heaters available today demonstrate operational savings and extended life when compared to traditional designs stemming from legacy plans for panel-heating systems. As energy costs continue to escalate, the energy savings options will provide faster startup times while reducing energy consumption. Manufacturers of ceramic infrared heating technology continue to investigate and implement materials and manufacturing processes that improve the service life of this robust, proven technology.
Ceramic infrared heaters have benefitted from continued innovation. While thermoforming machines often implement technology that reflects original panel-heater design, the thermoforming process can use flat-panel ceramic infrared technology to improve process efficiency and realize electricity consumption savings that pay for the heater upgrade inside of the first year of use.
When purchasing new equipment, it is important to ask about the heater build that is used in the equipment you will receive. Sometimes, a small incremental cost yields dividends for years. Even for existing systems, technology improvements can be applied via retrofitting. As the user of the process heating equipment, you have the most to gain and need to be your own advocate. New and emerging ceramic infrared technology can help you improve your competitive advantage.
Thermoforming Case Study Shows Operational Savings
In July of 2012, Volton of Montreal, Quebec, completed a cooperative study with thermoforming companies utilizing tubular heaters as the radiating heat source for their thermoforming process. They measured process electrical consumption at startup and during production. Volton then converted the equipment to use Elstein HTS heaters, and an independent company measured the energy consumption at startup and during production for the same output.
At startup, the HTS ceramic infrared heaters reached temperature within 2 min, whereas the tubular heater start up time to temperature ranged between 30 and 40 min. Further, to reach temperature, the tubular heaters required 105 kilowatts per hour compared to 65 kilowatts per hour for the HTS heaters.
The study shows time and energy savings at startup and during processing of HIPS polystyrene.
Similarly, Elstein performed a study where infrared heaters were tasked with heating 100 grams of water in a metal cup -- measuring the temperature at the bottom of the cup. The test studied:
While some may view infrared heaters as essentially similar, the study showed that energy efficiency is impacted greatly by quality of construction. The study demonstrated a 21 percent difference in efficiency between two similar looking FSR type heaters.