Functioning of a chiller

17/05/2019

We’ve already talked about heat pumps in a video in our Tempco Youtube channel, maybe skipping a step. That’s why I’m dedicating a new tutorial to the functioning of a chiller (english subtitles available), responding to many requests I’ve received.

Let’s start saying that we all have a chiller in our own homes: a refrigerator is indeed a chiller, working on the same physical principles. The explanation of the thermal cycle of a chiller can be commonly found in many sources on the web, involving cycles of compression, expansion, evaporation and condensation. I wanted better to underline an essential concept, being the fact that a chiller is not a ‘cold maker’, but it simply removes heat, using a refrigerant gas, or freon, as fluid thermal vector.

The refrigerant enters the environment to be cooled through a compressor, and passing through an evaporator, that is a heat exchanger, the gas evaporates. To achieve the status change from liquid to vapor, the gas absorbs thermal energy, heating up, cooling down as a consequence the environment’s temperature.

The gas reaches then the external condenser, another heat exchanger, where it cools down condensing and returning to a liquid state, dissipating the heat into the external ambient. The complete thermal cycle is then accomplished as a simple heat transfer cycle, from an environment to be cooled toward an outdoor space.

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Thermoregulation in recovery and refining of precious metals

10/05/2019

The treatment of precious metals is a very interesting and challenging field for thermoregulation applications. Recently, we’ve supplied a couple of thermoregulating units expressly developed for a customer specialized in the recovery and refining of precious metals. These last two thermoregulating units supplied joined the approx. 12 machines installed at the customer’s facility through the years, working on reactors employed in the refining process of precious metals.

The two new thermoregulating units are the result of the longtime experience of the previous installments and of the co-engineering with the customer, that requires in its production process very extreme and reliable equipments, ensuring continuous operations with pressurized water at the constant temperature of 135° C.

This peculiar need required the implementation of specific components, such as a Grundfos pump with special liquid-cooled seal. The thermoregulating units work with brazed plate heat exchangers in impact version for high pulsating pressures, specifically engineered for employ with steam and pressurized water. Modulating control valves and on/off pneumatic valves have also been installed, equipped with metallic actuators in order to stand extreme thermal stresses.

The units finally have a flowmeter monitoring the flow rate, a crucial factor to ensure the thermal exchange efficiency in the reactors. Pipings are all made of stainless steel, with flanged connections (and welded wherever they’re not flanged) and spyrometallic gaskets resistant to high temperatures.

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Fluid’s mixing in plate heat exchangers

03/05/2019

Many times I’m asked if fluids can mix in a plate heat exchanger. As I’m explaining in the new video tutorial on our Tempco YouTube channel (please turns on English subtitles), the only way it can happen is when a plate break occurs, due to corrosion of the plates’ material or cracking.

Further cases are avoided by the intelligent design of the gaskets in a heat exchanger. Fluids cannot mix indeed due to the break of a gasket, because gaskets in plate heat exchangers always offer a double protection.

Gaskets of a plate heat exchanger offer protection all along the perimeter of a plate and also in the nozzle area, where the liquid flows from a plate to another. Here, there is a double gasket, and in addition it offers a sort of drain toward the outside, so that in case one part of the gasket breaks there will be a leakage of liquid on the external side of the heat exchanger, alerting that something’s wrong is happening. Is then sufficient to stop the exchanger from operating and extract the two plates where the drop was detected, then close again the exchanger and re-starting the plant.

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Thermoregulation for electric vehicles test benches

26/04/2019

Electrification in the automotive industry is preparing a huge revolution in the mobility sector. The switch from the combustion engine to the new electric powertrain will bring several main transformations, leading to the request of new thermoregulation and cooling systems for test bench for electric engines to come.

2018 Chevrolet Bolt EV

Although a mass adoption of electric vehicles is still a far scenario – experts are expecting it to become a mass phenomenon in 10, maybe 20 years -, electric vehicles are already a reality on the market. There are still many aspects to be improved, such as the excessive weight of the battery pack and the insufficient recharge infrastructure, not developed enough to satisfy the power need of a large quantity of electric cars. In addition, if we try to imagine a future when everyone is plugging his electric car by night to the recharging station in his own home garage, there will be a serious problem to manage the high peak power demand. Here, IoT, connected cars and artificial intelligence will be strategic to develop new smart systems for the electrical grid management.

In addition, the rate of energy coming from renewable sources is still so poor, amounting to 17,1% in Italy of total power generation. The target of a sustainable mobility and decarbonization would be unattended if the energy employed to satisfy the demand of a mass fleet of electric cars comes from traditional and not renewable power sources.

Many leading automotive manufacturers in the meanwhile have already announced that they won’t be producing endothermic vehicles anymore within the next 5-10 years, and within the next 2-3 years every automotive manufacturer is planning to have electric car models for each of its offering segments. Thermoregulation and cooling applications for automotive test bench is an important application field also for Tempco, so that the transition toward a new electric powertrain will involve the development of new concepts of innovative test bench for electric engines, as it’s actually already happening.

Finally, the value chain of the battery pack industry is worth a mention. This industry involves a series of steps: European enterprises have the know-how to cover the production phase going from the battery pack to the control system, while there is a dangerous gap in skills and know-how on the first step, involving the processing of the activated mineral for the realization of cathode and anode and the production of electrodes and cells. This industrial sector is actually dominated by LG, Samsung and Sony, and by a few others eastern-Asia area manufacturers. On this purpose, Europe already launched some pilot projects, and a first call for interest was also launched in Italy, and ended last February, inviting all the potential suppliers to submit their interest to take part in the industrial value chain of electric cars.

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Piping connections in plate heat exchangers

19/04/2019

A frequently asked question from our customers in Tempco is referred to the possibility of swapping the connections of pipings in plate heat exchangers. That’s the topic I’m discussing in the new tutorial on our Tempco Youtube channel (please turn on english subtitles). In the majority of cases, the answer is Yes, it is possible, but there are also some exceptions so that is always better to ask for it in advance.

The request regards usually the possibility of reversing the direction of the flows, or to swap connections between the primary and secondary circuit. Plate heat exchangers generally have symmetrical hydraulic circuits, so that’s why it is usually possible to reverse the directions of the flows, that typically travel in countercurrent within the exchanger, and also to invert the connections between primary and secondary circuit. In both cases, the thermal transfer efficiency of the heat exchanger is not affected in a sensible way.

Anyway, is always better to ask in advance, because there are some applications with circuits that are not symmetrical, or with draining requirements. This is the case of steam, which must always enters the heat exchanger from above, so that condensation can go to the bottom in order to be completely drained from the exchanger. When using steam, it is then possible to swap primary and secondary circuit, but the direction of the flows cannot be reversed.

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Fibreglass in cooling towers

10/04/2019

The selection of technical solutions and the choice of materials in the construction of Cooling towers are guided by several factors, and principally according to the kind of water with which the plant is gonna operate. In addition to steel, another frequent choice is the fibreglass, offering a series of advantages that are clearly explained in this article.

Despite of a higher cost, due for example to the investments required in manufacturing equipments and dedicated moulds, fibreglass is the preferred choice of many manufacturers of open and closed circuit cooling towers for the realization of both components and structural profiles. The main quality of fibreglass is certainly the fact that, in constant presence of water, it does not oxides and is corrosion resistant, a main problem with chemically aggressive water, it is not affected by weather conditions and is therefore maintenance-free. Fibreglass in addition is lightweight compared to steel and metal sheets, and can be simply repaired in case of accidents returning to as new conditions.

The construction technique of the moulded components employs successive layering of glass fabric, called ‘mat’, which is then soaked in resin. Following the catalyzation, the resin and the mat layers are fused into one body, giving structural robustness and a uniform surface. A special orientation of the glass fibres can be engineered in order to better withstand and distribute static and dynamic loads.

Structural profiles are manufactured using a pultrusion (pull+extrusion) process with a dedicated die, employing a catalysed resin mixture blended with a continuous-filament fibreglass, ensuring mechanical and structural resistance.

The pieces are then coated with a UV-resistant gelcoat providing external protection, while the inside is waterproofed by applying a gelcoat with a paraffin additive aimed to prevents osmosis.

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What is and how it works a Heat Pump

05/04/2019

I’ve always had a problem with the term ‘Heat pump’, because I think it can be confusing. A heat pump is indeed a refrigeration unit with a reversible cycle, able to operate both for heating and cooling, as I’m explaining in this new tutorial on our Tempco Youtube channel (turns English subtitles on). As we all know, chillers don’t really ‘produce cold’, but they remove heat from the inside sending it to a condenser. That’s exactly what happens in the home refrigerators we all have in our kitchens, if we check the back of it we can feel it hot.

The heat pump thus operates as a refrigerator during the summer, removing heat from the ambient to be conditioned using a cold heat exchanger, called evaporator. Here, the freon evaporates removing the heat from air, liquid or fluid to be cooled, producing as an effect the perception of ‘cold emission’. The freon then carries the heat removed from the ambient to the warm heat exchanger, called condenser, dissipating the energy on the outdoor and thus emitting heat.

During the winter season, a cycle inversion valve swaps the functions of the two exchangers, transforming the condenser/heater into a cooler/evaporator that removes the heat from the external ambient, carrying it to the former-evaporator transformed into a condenser, that brings the thermal energy inside the ambient to be heated.

With very low ambient temperatures in winter, and high relative humidity, the external exchanger can often become completely iced, so that a defrost cycle is triggered automatically. The operating cycle is reversed for a few minutes allowing the hot freon to flow inside the external exchanger in order to melt the ice and restore its efficiency. During the operation, ambient heating will stop for a while, but it usually takes only a few minutes.

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Here comes iTempco, the Smart Thermoregulation IoT Platform

01/04/2019

Tempco is entering the Industry 4.0 with the iTempco IoT Platform for real time monitoring of industrial thermoregulation plants. Connectivity, big data and analytics are opening new horizons of possibilities in the thermal energy management, enhancing the levels of asset optimization and energy efficiency achievable thanks to the real time condition monitoring of equipments and data process analytics.

The iTempco IoT platform offers a variety of tools for the remote monitoring of equipments, with advanced functionalities of predictive maintenance, service and management of thermal machines, equipments and plants.

The user receives a hardware interface device pre-installed on the Tempco machinery, that enables the connectivity on the plant. The device provides the harvesting of data aimed to feed the iTempco dashboard for condition monitoring and fault detection, also allowing to adjust and modify remotely the configuration parameters of thermoregulating units and thermal machines.

The IoT applied to thermal energy management machines allows to maximize the production efficiency with costs optimization, increasing as well the equipments’ availability thanks to real time fault detection and data-driven predictive maintenance based on the actual operating status of the plants.

Let’s call it Smart Thermoregulation… are you ready to enter with us the world of Thermoregulation 4.0 with iTempco?

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Boiling water in a pot and pitting in plate heat exchangers

22/03/2019

A culinary tip gave me a good suggestion to treat the theme of pitting in plate heat exchangers. The answer at this link is indeed really interesting and clever, resolving the question if it’s better to add salt in water when cooking pasta before it starts to boil or when boiling has started. The article, in Italian, states that the proper thing to do is to add salt when water is already boiling, because the bubbles flowing up avoid the salt to deposit on the bottom of the pot, where in contact with the metal surface the solid salt absorbs the heat more efficiently than water, generating a highly corrosive contact surface between salt, water and the metal.

The resulting is pitting, ie a form of very localized corrosion with the creation of small holes in the metal. The case of when adding big salt grains in water during cooking daily habits explains very well the process leading to the pitting due to chloride concentration. We can indeed observe the very same phenomenon happening on plates of heat exchangers, when localized concentrations of corrosive elements (chlorides or other) cause the perforation of the plates.

Let’s grab an example with anodic oxidation.
In this case the fluid involved is sulfuric acid in high concentration, so that AISI 316 can provide a proper corrosion resistance against the chemical aggression. But it happens that, while the plant is in stand-by, there is product stagnation near the nozzles which leads to a concentration of the acid, causing in a medium-long period the pitting and thus the perforation for corrosion of the plates.

That’s why in this kind of application, and in similar ones, it is suitable to select a more resistant material, such as AVESTA 254 SMO, a type of austenitic stainless steel with high molybdenum content that ensures a specific high corrosion and pitting resistance.

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Biogas dehumidification for cogeneration

15/03/2019

More on cogeneration in our new tutorial video on the Tempco Youtube channel (turn on subtitles for english). We’re focusing in particular on biogas, one of the most employed fluids in cogeneration plants. Produced from organic waste, the biogas represent an excellent fuel for engines employed for heat and electricity combined generation.

We have here a very virtuous production chain, an example of what is called circular economy, recovering wastes to obtain power generation. Shell and tube heat exchangers are the suitable choice for biogas cogeneration applications. Previous to the proper combustion cycle, the biogas must be treated in order to eliminate all the polluting elements that it gathers and also to extract all the humidity contained, which in case of combustion can damage the engines irremediably.

Biogas treatment include a part of thermal treatment for the dehumidification of these gases, which are usually at the temperature of approx. 34-40° C. The biogas is cooled down using a chiller working at very low temperatures, about 0° C, combined with a shell and tube exchanger with the cold fluid (water and antifreeze) flowing inside the shell. The biogas flows inside the tubes. The tubes are usually straight and sliding to facilitate cleaning operations from deposits that the gas can gather, but also to drain all the water condensed in contact with the cold flow of the glycol water. The condense must drain perfectly and get collected in a condense separator on the outlet of the exchanger.

The application usually requires long exchangers, in order to allow the biogas to flow inside the tubes as long as needed to ensure the complete elimination of all the humidity. Dedicated blowers send then the dehumidified biogas to the engine, and sometimes it can also be post-heated to obtain a proper combustion temperature.

Construction materials are usually carbon steel for the shell, without expansion joints due to the short temperature gap involved. Headers can be as well made of carbon steel, while the tubes can be made of copper. In case the biogas presents high levels of aggressive and corrosive elements, both headers and tubes must have a full stainless steel construction.

The tubes are pressed and, my personal choice, welded, in order to avoid any risk of leaks of glycol water from the shell inside the biogas flowing in the tube section.

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TEMPCO researches and develops systems and solutions for cooling, heating, control temperature and heat exchange in different industrial processes.