Ohmic Heaters
An ohmic heater is an electrical heating device, which generates heat by exploiting the electrical resistance of the liquids.
These plants are also known as Joule heaters, because the heat is directly produced within the fluid itself by Joule effect, as alternated electrical current passes through the conductive material.
This process transforms energy, causing a rise of temperature.
We mostly rely on heat transferred from a hot surface, which is also the most commonly used heating technique for liquids.
Heat can be directly generated from a specific electrical heating element or indirectly from a hot means of transportation (e.g. steam) via a heat exchanger (e.g. shell and tube ,plate).
These methods require a temperature gradient to transfer the heat to the process liquid, therefore, the surfaces must be hotter than the product itself.
This gradient can cause fouling on the hot surfaces, which can burn, reducing heat transfer rates and adversely affect the final product. A further issue could develop when heating very viscous fluids or liquids with particulates, because it's difficult to achieve a uniform heat transfer.
Ohmic heaters address the aforementioned problems by removing hot surfaces from the heating of the fluids.
Applications
Our ohmic heating process has been used in food industry for over 20 years.
Emmepiemme offers therefore various types of installations and technical solutions to ensure a reliable and efficient process.
Various types of ohmic heaters have been developed over the past two decades, using new materials and advanced technology solutions.
It has been possible to build plants for heating treatments, pasteurization, sterilization, HTST (high temperature short time) for various categories of products, including:
- Fruit purée (peach, pear, strawberry)
- Fruit pieces (peach, pear, strawberry, pineapple, apricot)
- Vegetable cream
- Whole or pieces of vegetables
- Spreads and stringy paste cheese
- Egg products
- Dairy cream
- Algae
- Creamy and vegetable sauces
- Minestrone
- Jam
- Syrup
Benefits
-Small Size
-Fast Processing
-Up to 98% of energy efficiency
-No moving parts.
Features
Due to the above reasons, our ohmic heaters can process, uniformly and briefly (from 10 to 90 sec), both homogeneous and heterogeneous products. For the latter some precautions must be taken, e.g. regarding the composition of the carrying fluid, which electrical properties should be similar to the ones of the solid particles.
Ohmic processing approaches to some extent the HTST (High Temperature Short Time) concept, although the thermal damage to the product is remarkably reduced in comparison to conventional heating methods.
Sensory parameters in particular (like color, consistence and flavor) result much more satisfactory at the end of the heating process.
Aside from the reported quality improvements, industrial applications of Emmepiemme ohmic heater pointed out some further benefits in comparison with conventional heating methods, which are mentioned below.
Flexibility
Whether previously requested and arranged, a single equipment can be designed to be able to process both homogeneous products and products containing particulates. The processing of products containing diversified electrical properties is also possible in the range 1 to 30 times.
Elasticity
The absence of hot walls and quick heating gives the chance to easily stop and restart operation, and with very little product damage or loss, which is impossible with conventional systems and other sort of aseptic plants.
Modular construction
Emmepiemme ohmic heater is designed on a modular base. The single module is a 60 KW power unit; therefore it is possible, within its limits, to increase a plant power and capacity by simply installing additional modules.
Compactness
The overall dimensions of Emmepiemme ohmic heater are very reduced, thus it can be easily inserted even in existing lines, without problems as for layout or utilities.
Large-section pipes
This technology allows adopting large pipe sections (from 50 to 100 mm), so that the product pumping capacity is improved, especially for continuous plants, thus remarkably reducing the mechanical spoilage of products due to displacement.
Fluids containing particulates are more likely to lead to finished products with very large pieces (20 and even 25 mm), which are unlikely to be maintained in conventional systems.
This benefit also regards products with very high drained weight, e.g. up to 80-90% (depending on the specific product).
Commercial advantages
Because of the improved sensory qualities and the possible applications given by the aforementioned features, it is possible to put highly competitive and innovative products on the market, e.g. also including frozen products (IQF) as well.