Heat to electricity, the disruptive technology of Rectennas

Producing electricity harvesting heat with a device without moving parts could soon be a reality, thanks to several studies on development in laboratories all around the world on optical Rectennas. The Rectennas are a disruptive technology consisting in micro-antennas able to capture the electromagnetic waves at optical frequencies of infrared, produced by any object emitting heat, directly transforming thermal energy into electricity for efficient heat recovery.

Paul Davids Sandia National Laboratories Rectennas

A prototype of Rectenna has been recently announced by the physicist Paul Davids of Sandia National Laboratories in a publication featured on the Physical Review Applied. The micro-antenna developed, the size of a small finger nail, is made of aluminium in the upper side and by silicon doped with other several elements in the lower side, reflecting the infrared radiation. The addition on the lower face of a layer of 20 molecules of silicon dioxide works as a rectifier diode, capturing the alternating flow of electrons to create a current flow. The rectenna has been optimized and constructed employing materials of high availability and common use as much as possible, with methods allowing a production by actual semiconductors industries.


Rectenna thermal energy harvestingOptical rectennas thus represent a highly interesting alternative to thermoelectric generators, electrons generators from heat employed to power spacecrafts, requiring high temperature gaps in order to function, with high construction costs and offering low efficiency. Rectennas production could be cost-effective and practical, also at an industrial level and in bigger scale compared to the Davids’ prototype. This kind of device is also very reliable, and unlike electromagnetic generators doesn’t need to be in contact with the thermal energy source, thus less exposed to thermal stresses.





By capturing the infrared radiation, coming in continuous from the Sun and also dissipated by the Earth itself at night, the rectennas could operate as a sort of innovative photovoltaic technology producing electricity 24/7. At the moment Davids is looking forward to applications on harvesting heat from thermal plants, or to power devices such as spacecrafts that employ radioisotopes. Many years of further development are necessary in order to apply rectennas on harvesting sunlight and infrared radiation during the night time.

torri evaporative energia termica

Interesting advancements are anyway coming in several other laboratories around the world, such as the prototype of an optical rectenna aimed for sunlight harvesting developed by the Connecticut University, of the rectenna developed by Baratunde Cola in 2015 at the Georgia Tech Institute. The Cola’s rectenna is a carbon nanotubes antenna coupled with a diode composed by a layer of calcium, recently further enhanced settling a bilayer material composed of alumina and hafnium dioxide, increasing by 1.000 times the capacity, switching the current production from microvolts to millivolts range. According to Cola, optical rectennas could then be used to operate low-power sensors and powering IoT devices.

Legionella and cooling towers maintenance

Strictly related to cooling towers maintenance, as well as of HVAC and cooling equipments, the problem of legionella infections returned as an emergency last July in the north of Milan, in Bresso, with 11 persons hospitalized at the near Niguarda hospital. The Italian ISS, the Superior Institute for Healthcare, reports an increase by 17% of legionellosis in 2017 in Italy, compared to 1.700 cases occurred in 2016.

torri evaporative prevenzione legionella

Legionella is a group of bacteria commonly present in aquatic environments, that proliferates in presence of air and water at temperatures in a range between 25 and 50° C. The Legionella disease is transmitted by aerosol inhalation of a contaminated source, small droplets that are commonly found in HVAC and cooling machinery or with cooling and evaporative towers. A proper and correct maintenance of cooling towers is thus mandatory, in order to reduce the risk of infections.

legionella prevenzione


The measures are diverse, ranging from technical solutions such as the adoption of efficient drop separators, a construction of the plant that allows high accessibility for cleaning and service, avoiding stagnation points with proper drainage, and finally a water purification of the plant. Towers’ maintenance thus ensure not only maximum efficiency operating conditions of the cooling plant, but also a healthy environment where the evaporative tower is installed.

cooling towers legionella preventionThe IIS reports other cases of Legionella disease in the past: in 2016 in Parma a total of 42 cases of infections were related to a cooling tower of a local posts office. Many cases happened in Cesano Maderno, near Milan, from 2005 to 2008. The cause was not clearly identified, but infections stopped with the closing of many industries during 2008. At last, a Legionella epidemic happened in Rome in 2013, with 15 cases, due to a cooling tower of an important local commercial center.





Cooling in aluminium profile drawing

The aluminium profile drawing process involves cooling and thermal exchange operations combined with the treatment of the water employed for washing and cooling purposes.

trafilatura alluminio

The production of aluminium profiles is increasing globally, due to the growing demand of this kind of products more and more utilized in construction and building such as in several industrial applications.
Once the profiles are made, they have to be washed and cooled before going through the next production treatments.

raffreddamento trafilatura alluminio

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Heat pumps and deep-water dimple jacket TCOIL

We gladly and with great satisfaction dedicate a new article to an interesting application of TCOIL dimple jacket heat exchangers employed in thermal energy dissipation of a heat pump. The TCOIL dimple jacket exchangers are one of the most flexible solutions for cooling and heating purposes, able to adapt themselves to a wide variety of contexts and process needs.

scambiatori dimple jacket TCOIL pompe di calore

This time, we have installed the TCOIL directly in the deep-water, near the Como Lake, at the depth of 20 meters. Properly sized, the dimple jacket exchanger allows to convey the water of the heat pump using high-resistance flexible pipes.

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Eco-friendly and smart cooling

The concepts of green and eco-friendly stand for a variety of meanings. Usually, an eco-friendly plant is a system offering low or zero emissions.
But a plant can also produce emissions in the upstream of the process, so that the term eco-friendly can also be employed to indicate low energy consumption plants.

raffreddamento ecologico Tempco
Recent regulations are in particular promoting the adoption of EC electric motors, addressing and embracing the green trend in industrial machinery.
Tempco since a long time devotes big efforts to provide customers thermoregulation solutions, cooling and heating systems engineered in order to meet the heat exchange needs of their final applications, limiting the energy waste.

termoregolazione green Tempco

Several technical solutions are available to achieve this kind of goals:

inverters in ventilation groups
– inverters in pumping systems
– Modulating regulation systems using dedicated control valves
– Electric heating managed by static relays or SCR

termoregolazione intelligente ecologica TempcoThe integration of this kind of technologies allows to achieve huge and significant energy savings.
Thermoregulation units are usually conceived in order to offer high performances also in the most critical conditions. Thus, the units become redundant in case of average conditions or during advantageous environmental conditions.
The implementation of modulating systems able to adapt their operations to climatic conditions and to effective working needs (productions levels, temperature levels, etc…) allows to achieve a very efficient consumptions control.
These solutions can often require higher investments at first, but the advantages offered lead to a full ROI in a few months after the commissioning of the plant.


raffreddamento intelligente ecologico Tempco

Exhaust air treatment in textile facilities

The rameuses are machines employed in textile plants producing synthehic and technical fabrics in order to dry dryed fabrics or to hot fix them. This kind of machinery produces exhaust air that requires a proper treatment, but first of all it is necessary to decrease its temperature.

abbattimento fumi industria tessile

The application doesn’t require to achieve deep low temperature levels, as usually air temperatures of 40-45° C are sufficient.

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Fumes treatment in plastics coating plants

In the production of synthetic leather and other similar products, such as laminated composites, pvc, abs, polyurethane but also textiles and films, coating plants of plastic materials are widely employed. This kind of machinery usually produces exhaust fumes loaded with potentially polluting elements, and the fumes are sucked by dedicated exhaust hoods avoiding their dispersion in the environment.

scambiatori fumi spalmatura materie plastiche

Tempco realizes fumes treatment systems in coating plants as a complete solution, typically including a cooling tower equipped with pumping system and water recirculation, combined with a fumes/water exchanger, especially designed in order to decrease the temperature of exhaust fumes.

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Chillers in power generation plants

Chillers are employed also in power generation applications, especially in the case of biogas plants, usually related to cogeneration. Biogas is indeed obtained from waste discharge, animal, agricultural, food or municipal waste, presenting high presence of humidity and aggressive and corrosive agents. The biogas must then be dehumidified in order to be employed in internal combustion engines, and chillers are used to cool down the biogas, eliminating corrosive condensations that can compromise the combustion process and damage the engines components.

chiller deumidificazione biogas cogenerazione Tempco

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Cooling units for special furnaces

Carbon-ceramic brake discs are increasingly required in the automotive sector, for application on high performance vehicles, due to the extremely high levels of braking performances that they offer. The technology involved in the production process of this kind of brake discs is highly sophisticated, and requires a strictly confidential know-how.

Tempco is since a few years a trusted supplier of one of the leading builders of this kind of braking systems, having supplied already in the past a cooling unit solution for the furnaces.

raffreddamento forni dischi freno carboceramici

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Adiabatic free cooling at Plast 2018

Mita Cooling Technologies, a company specialized in cooling towers and a longtime collaborator of Tempco, will introduce the new PAD-V series of adiabatic coolers at Plast 2018, the international exhibition dedicated to innovative technologies for the plastic and rubber industry in Fiera Milano Rho, May 29- June 1, offering increased energy efficiency in an even more compact design.

adiabatic free cooling Mita PAD-V series
The PAD-V series is a free cooling solution for fluid cooling and the condensation of refrigerants, designed for heat dissipation capacities of 75 to 1.100 kW. The combination with chillers allows not only to suspend the employ of compressors during the winter season, with dry operations and leveraging on low temperatures of external air, but thanks to the adiabatic process the solution extends the benefits of energy saving also during the summer season.

Plast 2018

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