Custom Coiled Cable Immersion Heater with Thermocouple and Thermal Cutout

BCE Custom Coiled Immersion Heater
with thermocouple and thermal cutout.

A major US Aerospace company approached BCE in need of a custom heating solution.  

Their existing heating element failed to evenly distribute heat inside a water reservoir, leading to thermal stratification and hotspots. 

Additionally, while the customer's existing thermal system included temperature limiting devices, the new heater design required it's own thermal cut-out to ensure over-temperature protection and remove any possibility of a runaway condition.

The coiled immersion heater needed to satisfy the following:

• Temperature uniformity throughout the heated section (± 3 C)
• Hermetic seal 
• Over-temperature heater failure
• Thermocouple for additional temperature measurement
• 275 Watt, 115 Volt

OUTCOME

Click for larger view.

BCE designed a highly effective coiled heater with exceptional heat uniformity.  An additional
thermocouple was welded to the sheath of the heater to ensure accurate temperature measurement. A thermal cutout was placed into the NPT bushing and potted with thermally conductive epoxy to allow for heater failure if all other safety systems fail. 

BCE was able to design, create 3D models/ drawings, and provide the custom heating elements within a 3 week timeframe.

Contact BCE:
510-274-1990

https://bcemfg.com

Immersion Heater Application Note - Cooling Tower Basin Freeze Protection

Screw plug heaters used as basin heaters on cooling towers.

Industrial electric immersion heaters, more specifically "screw plug" immersion heaters are used in many commercial and industrial applications for keeping gases and liquids flowing at required temperatures. Cooling towers use screw plug immersion heaters for freeze protection of the cooling tower basin.

Cooling towers are an important part of many HVAC systems, providing comfort or process cooling across a broad range of applications. They function to remove system heat by dissipating it to the atmosphere through an evaporative process. They are common in many industries such as chemical processing, power plants, oil refining, and steel mills, as well as many other manufacturing processes where process cooling is required. Another huge market for cooling towers are commercial buildings including airports, shopping malls, hotels, casinos, conference centers, and

Cooling tower diagram with basin heater.

medical centers.

The purpose of a basin heater is to prevent water from freezing in the cooling tower basin during periods of shutdown or standby operation.

After the water passes from the top of the tower through the distribution system, it cascades down to the collection basin at the base of the tower structure. From the collection basin, the cool water can be pumped back into the system and begin the process all over again.

As a general rule, basin heaters are normally sized to maintain a 40°F basin water temperature at a 0°F ambient condition. When the system is running, the basin heaters should be powered off as the heater isn't required due to agitation and the heat load picked up during the cooling cycle. The heaters do need to be operational when the cooling tower enters standby or is shutdown for maintenance though. Thermostats, or other on/off controls, are used to tun the heaters on below 40°F  and when the cooling tower pumps are not running. The basin heaters are intended only to keep the basin water from freezing and not intended to act as freeze protection for other pumping or filling components.

Industrial Electric Immersion Heaters

Screw plug and flanged
immersion heaters
(courtesy of Durex)

Electric immersion heaters are used in a myriad of industrial applications. From drying industrial gasses, to freeze protecting cooling tower sumps, to heating acids in plating applications, the versatility of electric heating element can save time, energy and space.

Industrial immersion heaters are used to directly heat a standing or moving fluid by using electric heating elements. There are three primary types of industrial electric immersion heaters; screw-plug heaters, flanged immersion heater, and over-the-side heaters.

At the heart of industrial immersion heaters are the individual heating elements, normally constructed from a stainless steel or Inconel tube containing a magnesium oxide filler and a nichrome resistance wire. Current is applied to the wire which produces the heat, while the compacted magnesium oxide powder provides the electrical insulation, and the metallic tube provides the physical protection.