In this context, a highly innovative technology involves the use of CO2 as a refrigerant, replacing traditional refrigerant fluids, also helping to comply with new regulations for refrigeration applications aimed at reducing the environmental impact of the sector. CO2 is in fact a natural resource, available in the atmosphere but also as a waste product in numerous industrial processes. In this regard, rapidly growing are the technologies that ensure the capture, storage and use of CO2, called CCS or CCUS (Carbon Capture and Storage and Carbon Capture Utilization and Storage).

The properties of CO2 in fact make this gas a renewable resource that offers a high rate of heat transfer efficiency, which also increases the safety of applications in the event of leaks within the plants and at the same time guarantees a high potential for emission reduction, with a value of Global Warming Potential equal to 1.

However, in the compression, condensation and evaporation cycles of CO2 it is necessary to work with very high operating pressures, which reach up to 140 bar. A field that opens up new application perspectives for Tempco special brazed exchangers, which thanks to the particular brazing cycle are able to withstand very high working pressures.

L'articolo CO2 refrigeration for a more sustainable conditioning proviene da Tempco Blog.

Also in 2023 we have installed a fair number of biogas plants, all equipped complete with chiller, heat exchanger and condensate separator.

All systems are always supplied in full configuration and are delivered ready for installation. Speaking about biogas, of particular interest are therefore the latest applications in the paper mill sector, with the aim of reducing polluting emissions. In fact, paper mills have a high potential for the production of biogas and biomethane, as the production cycle of a paper mill generates large amounts of waste water rich in biodegradable COD (chemical oxygen demand), which lends itself to being treated and valorised for the production of biogas.

L'articolo Chillers, exchangers and separators for biogas treatment proviene da Tempco Blog.

This development therefore allows the use of air-cooled condensers, the classic dry-coolers, adopting a solution that also offers the advantage of eliminating the water consumption involved with evaporative towers and ensuring a much simpler overall maintenance of the plant. In fact, there is no longer the risk of legionella implications due a poor water management or scaling due to the presence of carbonates.

The cooling solutions for the production of expanded polystyrene developed by Tempco therefore use special heat exchangers equipped with stainless steel tubes, a material chosen with the aim of increasing their durability and reliability over time.

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L'articolo Dry cooler in expanded polystyrene production cooling proviene da Tempco Blog.

A thermal machine that can be a dry cooler, or a refrigerating group, or a cooling tower. In this case, there are indeed four parameters required for the proper sizing of the machinery: the kind of fluid to be cooled and its flow rate; the inlet temperature, which is the temperature of the fluid as it comes from the process; the outlet temperature, which is the temperature of the fluid required when it goes back to the process; the design ambient air temperature.

Ambient air temperature that in case of a chiller is related to the condensation process, in case of a dry cooler is the temperature of the air that will cool the fluid. And finally, in case of an evaporative tower is the wet-bulb temperature, a key value for the evaporation process.

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L'articolo Thermal machines and the Four fingers rule proviene da Tempco Blog.

CO2 employed as a natural refrigerant gas (R-744) is an excellent alternative to traditional synthetic refrigerants (CFD and HCFC), offering a 0 value of Ozone depletion potential (ODP) and a GWP (Global warming potential) of about 1, far less than that of traditional refrigerants. CO2 has also a very high thermal transfer coeffient, much higher than synthetic refrigerants, is stable and non-toxic, but has to work at very high pressure levels, thus requiring higher standards for the design of refrigeration systems and components. Otherwise, its excellent flow performances allow to significantly reduce the size of compressors and refrigeration equipments, making the overall system more compact.

Furthermore, CO2 is a natural working medium of easy access in the environment, and is also a by-product of many industrial processes and factories, so that refrigeration using CO2 represents an excellent solution for the recovery and recycling of exhaust gas.

Another very important application for high temperature brazed plate exchangers involves fuel cells, using hydrogen which is a optimal candidate for energy of the future as alternative to fossil fuels. Fuel cells are zero emission power generation systems that employ an electrochemical process to obtain electricity and heat from the chemical reaction between hydrogen and oxygen, generating water as by-product. Therefore a totally green and clean power generation solution.

Nowadays there are several and different fuel cells technologies deployed, and brazed plate exchangers are employed in a series of tasks such as pre-heating of air and fuel, cooling of the cell and humidity and vapour management, through energy recovery of the generated heat. All of these applications have in common high temperatures requirements, as well as high corrosion resistance.
In the schemes below, there is a series of examples of brazed plate exchangers applications in different fuel cell related technologies, used in micro-grids, sustainable mobility and for hydrogen production.

Among them there are Solid oxide fuel cells (SOFC) employing exchangers for air pre-heating and heat recovery of thermal energy generated by the oxidation process of hydrogen. In Proton-exchange membrane fuel cells (PEMFC), high temperature brazed plate exchangers are used for heat recovery aimed for water heating. Brazed plate exchangers provide hydrogen pret-heating and exhaust gas heat recovery in trucks using fuel cells, making heavy-transportation sustainable. Finally, brazed plate exchangers are used for ammonia pre-heating in NH3 cracker systems, employed for hydrogen production from NH3 molecules.

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L'articolo High temperature brazed plate exchangers in the hydrogen industry and CO2 refrigeration proviene da Tempco Blog.

I remember when first attempts started on the market to employ inverters in order to adjust the speed of compressors on refrigerating groups. Inverters are largely employed to regulate speed on electric drives, adjusting the power absorption based on the season conditions. It’s clear indeed that during the summer season, when ambient temperature is higher, a refrigerating group needs the maximum power in order to achieve the refrigeration task required. While during the winter season it requires less amounts of power, due to a series of reasons such as the increased efficiency of the condensation system and the fact that water comes from the production process at lower temperatures.

The study to implement energy saving on refrigerating groups aimed then at adjusting the speed of fans on condensers using EC motors, with electronic control, through inverters. This allows the regulation of the speed of fans based on ambient temperature levels.

The same kind of adjustment was then possible on compressors. Let’s make an example to explain why: when sizing a refrigerating group employed to regulate the temperature of pharmaceutical reactors, the plant must be engineered to provide the maximum capacity required to achieve the cooling task. But there will be also a series of intermediate steps not requiring the maximum design refrigerating capacity, but maybe only at 50% or 30.

In the past it was used to employ multi-compressor plants, with step-compressors, using all of the compressors, or only 2 on 4, or one on 4 for example. The solution allowed to obtain a good energy saving, clearly using a step-approach. Which means, having a four-compressors plant, the possibility to have a 100% capacity, or at 75, 50, 25 or 0%.

A further improvement was to install a collecting tank in order to accumulate refrigerated water to satisfy peaks and hollows on the thermal work diagram. An optimal regulation, that can be furthermore improved.

The improvement consists in the employ of an inverter, which allows to adjust the speeed of the compressor in order to have the correct amount of power at the exact right moment when it’s needed. Which represents the very perfect condition. I remember that the first attempts to install inverters on compressors failed, because these were volumetric piston compressors that when powered by the inverter kept stuck.

The problem has been solved with the adoption of scroll-type compressors, that can be used with inverters. Taking a huge step forward in energy saving applied to refrigerating groups. There are also other possibilities to further enhance energy saving, such as using inverters also on pumps to regulate the pressure, but let’s discuss it in a next video.

L'articolo Energy saving with inverters in refrigerating groups proviene da Tempco Blog.

In addition to the measures aimed to replace the kind of refrigerants employed, the constructors of refrigeration equipment are indeed very committed in reducing the amount of gas within the machines. The B series brazed plate exchangers have a patented asymmetric plate design which optimizes the efficiency requiring much less refrigerant, with lower water pressure drop under the same working condition compared to different series.

B series brazed plate exchangers are also compatible with natural refrigerants and alternative refrigerant fluids R290, R32 and R454B with low GWP (Global Warming Potential), pursuing the target to cut CO2 emissions and reduce the environmental impact of the refrigeration sector.

The series offers the following advantages:

• Reduction up to 44% of refrigerant
• Reduction up to 25% of water pressure drop
• Increase up to 19% of water flow rate

A similar approach is also employed in modern air condensed machinery, that more and more are realized using a micro channel design.

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L'articolo Sustainable refrigeration with asymmetric brazed plate exchangers proviene da Tempco Blog.

Biogas is a natural fuel, but in order to be employed in cogeneration plants it requires a special dehumidification treatment. This is achieved using systems composed by a chiller and shell and tube exchangers, especially engineered for this kind of application, which cool and dehumidify the biogas using a very cold mix of water and glicol.

In fact, biogas coming from digesters enters the system at temperatures of 35-40° C, and must be cooled at temperatures of approx. 4-5° C, eliminating the maximum possible amount of humidity contained. At this purpose, chillers at very low temperatures are employed, near the freezing point, at +1° C or +2° C.

On the outlet of the exchangers the biogas will then have a relative humidity of 100%, but with an extremely low absolute content of humidity. Installed on the outlet of the exchangers there are also condense separators, big tanks aimed to collect the condenses. Furthermore, on the output of the systems there are also additional filters, providing a further filtration of the biogas, which then is finally ready to enter the engines.

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L'articolo Shell and tube exchangers in biogas treatment for cogeneration proviene da Tempco Blog.

The exchanger TCB3000A combines a series of patents and is made with stainless steel chevron plates and high purity copper foil. It allows to reach high compactness, with a size reduction by 50% compared to other similar equipments. The solution offers high transfer efficiency and high corrosion resistance.

The patented design of the TCB3000A exchanger integrates an air pre-cooler, a water separator and an evaporator in a unique thermal machine, ensuring low pressure drop and low dew point.

In its working circuit, air compressor compresses hot and moist air to the pre-cooler of the A Series exchanger, where hot and moist air exchanges heat with treated cold air. The chilled moist air then enters the evaporator, lower down its temperature and condensate water out by evaporation. On the next step, the air moves to the separator where condensate water gets separated from air thanks to centrifugal force and gravity. The exclusive no-mesh design of the separator avoid problems of ice and oil-clogging, without the use of filters and ensuring long working life. Finally, the cool and dry air goes back to the pre-heater to be heated to the required working temperature.

The unique 3-in-1 design allows to use directly outlet air, achieving a significant energy saving. The solution is also clogging free and easy to maintain, and is equipped with special patented leakage testing connectors.

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L'articolo New product, compact 3-in-1 brazed plate exchanger for air dryer proviene da Tempco Blog.

Thermal energy is a very common presence in industrial production. Heat is indeed required in a number of production processes in industries such as food, industrial, textile, glass and ceramic industry, chemical, oil & gas and metallurgy.

Many among these industrial processes involve waste materials, and thermal energy is one that gets often lost at the end of the process. This is usually referred to as waste heat, and it can be present in several forms: fumes coming from furnaces combustion, or from internal combustion engines, turbine’s or cogenerators exhausts, steam coming from heat treatment plants or from drying tasks, just to name a few.

Within these same production processes, in a different step of the production line, a cooling system is then often required, also employing thermal energy but with a negative value, meaning a need for thermal cooling.

All these cases are suitable for the application of equipments that enable to employ that same waste heat to obtain chilling power, without further expenses in terms of primary energy consumes, by mean of heat recovery of the waste energy.

Waste heat can be divided in three classes: high energy, exceeding 650° C, mid temperature, between 225° C and 650° C, and low temperature, up to 225° C.

High and mid temperature waste heat are the most useful and ‘precious’, because they can be employed both directly or to feed further machinery such as cogenerators (combined production of heat and power) and absorbers, aimed to the production of chilling power. Low temperature waste heat can thus be employed in the form of hot air or water for heating purposes or pre-heating of further production processes that require low temperatures.

Cold production from mid-high temperature waste heat
The essential components of a machinery for cold production from waste heat are basically:

– waste heat at temperature higher than 220°C, with a proper flow rate
– heat exchangers, to achieve the thermal transfer from waste heat (such as exhaust fumes of a furnace) to a thermal fluid (diathermic oil or pressurized water)
– a circulating circuit for the distribution of the thermal transfer fluid to the absorber
– an indirect fired absorber for cold production

The overall system only require additional power for the operations of accessory equipments, such as circulating pumps and fans.

Power Fluid absorber units by Robur
Robur Power Fluid absorber units are an example of efficient thermal machines that allow to ‘produce cold’ leveraging the thermal heat coming from a technological process. The working cycle of the units is showed in this scheme.

The thermodynamic cycle employs a solution of water and ammonia, in a hermetic closed circuit that avoids refill, substitution and disposal operations. The thermodynamic cycle is triggered by the waste heat flow, heating the generator by mean of a coil, in which diathermic oil or pressurized water are flowing.

Condensation happens in air, without the need of a cooling tower, thus avoiding the related hydraulic circuit and control devices.

These units enable to produce cold water to be employed for air conditioning, production processes cooling or even for food preservation, being able to supply cold or chilled water down to -10° C.

Advantages of Power Fluid units
Each industrial process involving the presence of waste heat above 200° C and the need of chilling power can benefit from these absorber units, such as metallurgy industry, chemical, glass or cement industry, agrifood and dairy, achieving high energy savings and maximizing the efficiency of the overall production process.

Further advantages offered by Power Fluid units are:

– easy engineering and installation of the plant, not requiring cooling towers and suitable for outdoor installment, with small footprint
– high reliability, thanks to an almost static refrigeration cycle (only two moving parts are employed, including fans) ensuring long life span without efficiency decrease
– wide operating range, in terms of both external air (condensation) and outlet cold water, which can be supplied even at low temperatures of -10° C
– no particular permissions nor authorizations are required, since refrigerants are not employed, replaced by the use of ammonia, a totally natural and eco-friendly refrigerant (near zero ODP and GWP values)
– economically convenient, especially if the unit can be used for many hours/year, being that the chilling power obtained is actually for free

Preliminary feasibility conditions of the recovery plant
Some conditions must finally be verified for a first evaluation of the solution:

– Availability of waste heat at temperatures higher than 220-240° C. This is a mandatory condition to obtain a sufficient transfer fluid able to feed the absorber and effectively trigger the thermodynamic cycle

– concomitant presence of heat recovery and need of chilling power. The cooling energy supplied by the absorber is always subjected to the presence of waste heat to feed it. When chilling power production exceeds the cooling need it is also possible to store it, but it involves higher investments in the chiller circuit to be carefully evaluated
– Estimation of operating hours/chilling power required in order to calculate the ROI. The overall amount of chilling power produced will cover the costs of the plant, so that the higher the indicator is, the shorter will be the ROI.

L'articolo Absorption chillers, free and green refrigeration power from waste heat proviene da Tempco Blog.