High efficiency of plastic electric heated plates

Jordi Gasull. Rotecna R+D Department.

The use of heating plates in farrowing and weaning and the correct regulation of these are vital factors to ensure the welfare of piglets. Good handling of the plates guarantees the thermal comfort and the proper development of the piglets, reducing mortality in their first hours of life and improving their adaptation to the weaning phase.

OBJECTIVE

To show the energy efficiency and comfort of Rotecna electric plates, various comparative tests have been carried out that demonstrate the suitability of Rotecna panels made of plastic compared to other polymer stainless steel coated models. On the other hand, the study also demonstrates the greater efficiency of Rotecna's probe-adjusted heated plates since it allows a more precise configuration, which reduces electricity consumption. 

EFFICIENCY OF PLASTIC PLATES VS. STAINLESS STEEL COATED POLYMER

This study has analysed the consumption of different models of heated plates depending on the material. Specifically, Rotecna's heated plates, made of plastic (1200x500 mm with probe), have been compared to another model on the market made of polymer coated with stainless steel sheet (1200x500 mm with probe). 

In the test, the two plates were installed and run at the exact required temperature (34 ° C) with identical thermostats and in the same room with the same environmental conditions to track the accumulated consumption. The plates were controlled with a surface probe thermostat (on at 100% of the voltage below the target temperature and off when the target temperature is reached).

A thermocouple surface temperature measurement was performed on the stainless-steel coated polymer plate since infrared measurement does not give a reliable reading on stainless steel surfaces. The controller was calibrated to match the probe reading. In addition, the probe area was covered with an insulating material to simulate the effect of occupation by animals.

The data recording was done over 21 days, in which both plates worked in the same environmental conditions and with the temperature adjusted to similar values in the two models. 

Test conditions:

• Ambient temperature: Approximately 21 °C.
• Required temperature: 34 °C.
• Duration of data recording: 21 days.

After the first six days and 15 hours of functioning, the difference in energy consumption recorded was 23% lower with the Rotecna plastic plate, which recorded consumption was 5.55 kW (34.7 W/h on average), while that of the stainless steel-coated polymer plate was 7.25 kW (45.3 W/h on average). On the other hand, after 21 days, at the end of the test period and having produced slight changes in ambient temperature, the difference in consumption was 14%, also in favour of the Rotecna plastic plate. 

In summary, during the test, strictly comparing the product without altering the process with different regulation systems for each model, with the same controller and probe taking the surface temperature in both cases, the result has always been favourable to the Rotecna heated plate.

We understand that, among other differences, the metal plate acts as a radiator, transmitting more heat to the room environment, making it less efficient, from an energetic point of view, to sustain a constant temperature.

REGULATION SYSTEM WITH PROBE VS. POTENTIOMETER

Another of the tests of the study focused on quantifying the difference in consumption between plates with a regulator without a probe (regulation by voltage percentage) and plates with a thermostat with a surface probe (at 100% of the voltage below the target temperature and off when the target temperature is reached).

For this test, two 1200x500 mm 150 W Rotecna electric plates were fixed, which worked simultaneously with the free surface and in the same room to ensure that the environmental conditions were the same for both models to be compared. The manual regulator without probe was adjusted to obtain a surface temperature that coincided with the desired surface temperature on the other plate to be compared (regulator in position at 70%). For the probe thermostat, the temperature detected by the probe was checked to match the actual surface temperature of the plate.

When starting with the consumption record, both plates had the same surface temperature at the same point.

Test conditions:

• Ambient temperature: Approximately 21 °C.
• Required temperature: 36 °C.
• Duration of data recording: 2 days.

After testing and data analysis, we concluded that the consumption results of the plates are very similar. However, the probe offers the ability to self-regulate the temperature, while the system without a probe requires manual regulation. On the farm, this can lead to savings of up to 5% by adjusting the temperature more precisely with a probe than when done manually, depending on the animals' behaviour. On the other hand, the savings can reach up to 35% with the probe since the plates automatically switch off when the animals generate enough heat to keep the plate at the desired temperature, being on a perfectly insulated surface. In addition, a temperature curve can be applied to the plate as the piglets grow. It should be noted that plates made of highly conductive materials should never be turned off since, at room temperature, they will always absorb heat from piglets.

PIGLETS' WELL-BEING AND COMFORT ACCORDING TO THE MATERIAL

The feel of the surface, the temperature distribution, the tightness, the lightness and the fastening system of the plastic plates are some of the safety, comfort and well-being advantages compared to other porous, heavy materials that dissipate more heat.

Main advantages of plastic plates compared to polymer plates coated with stainless steel:

• They require a smaller amount of energy to reach working temperature. 
• They dissipate much less heat to the environment, mainly if no nest is used.
• They have excellent thermal inertia, so they hardly vary the temperature during which piglets will suck, which facilitates their regulation.
• Being insulating, they do not absorb heat from the animal even if they are turned off.
• They distribute the temperature on the surface more homogeneously.
• They have a surface with better grip for the legs of the animals, which is especially important in narrow squares with plates placed in the centre since the piglets usually suckle by pushing on the plates with their hind legs.
• They provide a surface with better comfort for rest, being plastic, a softer material than stainless steel or polymer cement.
• They have a support system without corners where dirt can accumulate, facilitating cleaning tasks and making them more hygienic.
• Lighter weight, between 3.5 and 9.5 kilos. On the other hand, concrete plates weigh more than 30 kilos.
• About the two previous points, both for the type of support and the weight, can be set much better than the joists that support the floor, which means less effort and prevents them from moving sideways due to lack of support, which is vital if the plates go against the wall.

CONCLUSIONS

After performing all the comparative tests, the results conclude that, in every scenario, Rotecna heated plates made of plastic are more efficient, with energy consumption savings ranging between 14% and 23%. Although the percentage may be variable due to the different working conditions on each farm, it is apparent that the results, in all cases tested, have been favourable to the Rotecna plastic plate. On the other hand, using plastic as a material also provides greater efficiency by preventing heat from dissipating to the environment and maintaining a homogeneous temperature on the surface of the plate so that piglets do not lose their body heat. In addition, its soft and comfortable surface provides a unique non-slip finish. Finally, it should be added that if one works with nests with the heated plates, the energy savings can be even more noteworthy since, in particular environmental conditions and with a certain age of the animals, it may be viable to have the heated plate turned off, the microclimate created by the animals inside the nest being sufficient. In this case, with plastic plates, it would be like having a blind plastic slat on the ground, so the thermal feeling is not unpleasant for the animals. On the other hand, if the plate is metallic, the cold feel of the metal is not pleasant for the comfort of the piglets.