FAQs

  • Thermal Energy Storage
  • Tubine Inlet Air Cooling
  • District Cooling
  • District Heating
TES

Know more about Thermal Energy Storage

  • Establishment of the TES application and whether it will be combined with a District Cooling plant, Gas Turbine Power Plant or Mission Critical/Emergency Cooling Systems, as the elaboration of each of these systems is different.
  • Proper study of the TES system, including plants details, components, system size, operating patterns, temperatures, demand needs, and more.
  • Selection of the optimal TES technology in accordance with the client’s requirements, whether it be a naturally stratified chilled water tank, ice storage, or other Thermal Energy Storage method.
  • Design of tailor-made diffusers for your TES Tank.
  • Cutting-edge simulations of the tank with Computational Fluid Dynamics, which uses complex equations and modeling to evaluate the performance of the TES systems by assessing thermo-fluid variables.
  • Selection of state-of-the-art measuring and control equipment to adequately operate the TES systems without affecting their thermal performance.
  • Reduced capital costs due to sizing for average demand.
  • Increased electrical efficiency by reducing power consumption by coordinating with peak power demands.
  • Decreased use of other fuels through a more efficient operation.
  • Evening out of cooling system loads by drawing stored energy from the thermal tank.
  • Use of excess capacity during off-peak hours to meet peak cooling demands.
  • Reduction in greenhouse gas emissions and pollutants.
  • Less wasted energy and resources.
  • Possibility to combine with TIAC, DC, and Data Centers, among other applications.

Thermal Energy Storage is very beneficial combined with TIAC for peak power production, when extra power production is required for certain hours per day (3 to 8 hours per day). The combination of Thermal Energy Storage and Turbine Inlet Air Cooling is called TESTIAC.

The chilled water stored in the thermal tank can be used to provide turbine cooling in facilities that use gas turbines, like a GT Power Plant. TIAC helps increase turbine power output in facilities situated in areas with extreme ambient conditions. A TESTIAC configuration would add to the overall efficiency of the plant.

Of course! District Cooling plants can absolutely take advantage of TES technologies. Thermal Storage offers many benefits for DC plants: operational optimization particularly at peak load periods, increased efficiency, increased plant reliability and availability, etc.

Most new District Energy plants already incorporate TES. Even, older DC plants can be retrofitted with thermal storage capabilities, providing the added benefit of an optimized peak cooling response. TES technologies can also offer back-up cooling for DC systems during outages, maintenance, or during component failure.

Thermal Energy Storage has many environmental benefits compared to alternative methods, such as a lower carbon footprint, reduced greenhouse gas emissions, decreased use of additional fuels, and energy conservation. All these elements contribute to TES being a more environmentally-friendly solution.

TES Tanks also count toward LEED credits. Did you know that off-peak power is cleaner than peak power? It’s a fact, and Thermal Energy Storage can help you reduce demand during peak hours and minimize consumption of electricity and fossil fuels.

Governmental authorities of the Middle East, where there is huge population growth and rising power demands, have already implemented state-mandated requirements to install Thermal Storage technologies. Additionally, the Paris Climate Change Agreement has forced governments worldwide to consider using more sustainable TES systems over alternative options.

  • Thermal Energy Storage Tanks: Our most popular tank is the Stratified Water Tank, in which natural stratification separates the warm and cold water. The Ice Storage Tank is another option which generates ice on cooling coils.
  • Above ground or underground TES tanks
  • Steel or concrete TES tanks
  • Tailor-made diffusers: Diffusers are used in our Stratified Water Tanks to maximize the efficiency of the TES system by minimizing the thermal losses. Radial and Slotted Pipe Diffusers are two of our most popular models.
  • TESTIAC: The combination of TES and Turbine Inlet Air Chilling components.
  • More! Get in touch with ARANER to find your solution.

CFD has revolutionized the industrial design as a key tool for the detailed analysis of the fluid motion and heat transfer. Beyond traditional approaches, CFD adds a superior understanding and insight into the complex phenomena of thermal energy storage and generates essential results about the design of the TES system for each particular project.

In simple terms, Computational Fluid Dynamics speeds up the design process of TES systems and simulate how the tank will function by modelling the tank’s inflow and outflow, as well as the behaviour of the thermocline layer. CFD considers a wide variety of parameters: velocity, temperature, fluid properties, turbulence, etc.

Computational Fluid Dynamics can only be performed by CFD specialists. ARANER’s engineers are experts in CFD simulations, which not only requires specialized knowledge of physics, but also requires knowledge of a highly-advanced software and design tools.

As mentioned in the section called “What are the main benefits offered by tes technology?”, TES facilitates sizing for average demand, meaning that in additional to reducing capital costs, you may also be able to reduce your plant’s dimensions.

For TES, there are 2 footprint options: an above ground tank or an underground tank. If footprint limitations are an obstacle, ARANER will study your project to come up with the best solution for you. Underground TES tanks can be buried below natural areas, parking lots, or in the basement of your facility. Buried tanks also do not influence the aesthetics of your plant.

ARANER engineers closely work with our clients in order to assess their cooling needs and propose the best solution. Based on the cooling consumption curve, the cooling production can be optimized between the cooling supply from chillers and TES tank.

The TES operation simulation allows ARANER specialists to assess the operation of chillers in conjunction with the sizing of the TES system.

Typically, the performance of any chilled-water storage tank is measured in terms of the Figure of Merit (FOM). According to ASHRAE, the FOM is the ratio of the amount of cooling removed from storage to the amount of cooling theoretically available from fully charged storage. It takes into account the loss of usable stored cooling capacity due to thermal conduction and mixing in the tank due to thermocline thickness and loss of temperature differential.

The Figure of Merit depends on the aspect ratio of the tank, operating practices and mainly on the design of diffusers. Stratified chilled water tanks with well-designed diffusers typically perform at FOM levels of 85-95%.

TIAC

Know more about Turbine Inlet Air Cooling

  • Proper study of the gas turbine filterhouse shall be performed to minimize the Filterhouse modification and introduce the extended surface heat exchangers (ESHX) the most efficient way for indirect cooling.
  • Proper simulation of the cooling demand shall be performed to optimize the size of the chillers and thermal energy storage.
  • Selection of the heat rejection method is also important (cooling towers, air cooled devices, seawater or river water cooled systems). The simulation will also be helpful to determine the most feasible solution by comparing the energy and water consumptions all around the year.
  • Selection of the state-of-the-art equipment chillers with highest efficiencies, VFDs for pumps etc.
  • Proper control system with robust equipment to avoid failures and blackouts. Also the control will be very important to make the plant work with correct efficiency and mitigate the low delta-t problems.
  • Selectable and constant inlet air temperature with ARANER Adaptative Temperature (AAT).
  • Fast system delivery compared with new turbine installation.
  • Avoid GT output fluctuation produced by ambient conditions.
  • Lower price per generated megawatt compared with new GT plant.
  • No extra auxiliaries’ equipment needed (same transformer and generator).
  • Recognized green technology with carbon credits.

Gas Turbines OEMs accept our system case by case when we work with them, as long as it complies with several requirements such as a limited pressure drop, uniform temperature distribution, and appropriate selection of materials for the GT Filterhouse modification.

In ARANER we have worked with several OEMs such as MHPS, GE, ANSALDO or SIEMENS among others.

Especially when the turbine inlet air cooling is needed only during some hours a day (peak demand), it is extremely beneficial to implement a TESTIAC configuration, which combines TIAC with a Thermal Energy Storage Tank.

With a TES Tank the net increase in power output is maximized and the cooling plant required is reduced, reducing also the cooling plant cost.

TIAC has been demonstrated to be a cost effective environmental energy solution for the power generation industry reducing emissions of pollutants and providing more efficient and sustainable power plants.

TIAC reduction on carbon emission has been well recognized by international institutions. The United Nations Framework Convention on Climate Change (UNFCC) prepared a report which illustrates the reductions in CO2 emissions due to the increase in efficiency and reduction in fuel consumption of the combined cycle in Jebel Ali Power Plant (Dubai).

A total of 65,799 tons of CO2 were reduced during the monitoring period between January 2013 to December 2014 (5.54 % reduction when compared with the emissions without TIAC).

Turbine Inlet Air Cooling (TIAC) is not only the most effective solution for power augmentation in gas turbines, but it also reduces carbon footprint at the same time. TIAC technologies are able to produce the same power output than a new turbine, however with lower installation cost and higher efficiency of fuel utilization.

Regarding the operability and maintainability issues for TIAC system, it is very easy. Thanks to our control system the TIAC plant operates automatically.

ARANER’S TIAC control system has a very simple and intuitive HMI. Very few and simple orders are required from the operator. The level of difficulty is very low, and after 1 day training, operators will master the system.

The maintenance is very easy. Main equipment of TIAC system are compressors, pumps and heat exchangers. All equipment to be installed is robust, industrial grade and tested on site to assure their correct performance. From our experience, important damages on TIAC equipment are very rare and they always result from an incorrect maintenance.

The main maintenance operations required are related to the water pumps and the compression units, and these are very basic compared to the general maintenance of the power plant.

Maintenance staff at the power plant is normally used to maintain these kind of equipment. This means that the same operators from the power plant can operate and maintain also our TIAC system.

The basic maintenance activities are limited to a chemical analysis once per year, the cleaning of the water and oil strainers, change of bearings once they have reached their service life and, an overhaul of the main equipment every 5 to 6 years.

All the required maintenance procedure and frequencies are included in ARANER’s TIAC maintenance manual to avoid any trouble during operation.

The only point of interference between the TIAC plant and the gas turbine is the Filterhouse, where the Extended Surface Heat Exchangers (ESHX) are installed.

The gas turbine filterhouse modification period usually takes around 1-4 weeks depending on site conditions and the filterhouse size, and will be coincident with the gas turbine annual maintenance period, so no additional shutdown is required.

The only specific required action is a good coordination between the GT annual maintenance operation and the filterhouse modification so both of them can be carried out in parallel.

It must be clean water, but there is no additional minimum quality requirement because chemicals are injected during the filling of the system at the commissioning phase.

As the chilled water circulates through a closed loop, no continuous make-up water is required. No continuous chemical injection is required either. It is only recommended to perform an analysis of the water quality every year.

Typical frequency of chemical injection would be every 5 years, depending on many factors such as the use of the water or how clean the installation is.

This is practically distilled water and at chilled temperature. From our own experience, it is typically used as make-up water for other processes in the plant, but it could be used also for irrigation or even Air Conditioner units if they are close to the turbine.

The condensate quality will depend on the system’s cleanliness and the quality of the filters inside the filterhouse. As it is an open circuit, this condensate water will take particles of dirt from the pipe with it, also from the filters if not properly cleaned, etc.

For this matter, an in situ analysis must be performed and if the resulting quality is not correct, then the appropriate filtration system should be installed to fit the condensate’s later use.

Negative. The extended surface heat exchangers (ESHX) are installed after the filters in the gas turbine Filterhouse. The pressure drop of these heat exchangers is very low and limited below a maximum value established by the OEMs themselves to make sure that the gas turbine production is not affected.

Besides, the pressure drop introduced by the TIAC system is far less than the pressure drop related to dirty filters that are not correctly maintained.

Since the power output of the gas turbine increases when the TIAC system is installed, the capacity of the gas turbine auxiliaries, such as the generator and the power transformer, shall meet this increase of power as well.

Gas turbine generators and power transformers are usually oversized so that they never limit the gas turbine production in any ambient conditions.

However sometimes the capacity of these equipment cannot meet the power increase of the turbine, and therefore they need cooling as well. In this situation, the same TIAC system can refrigerate them also in order to meet the increase of capacity.

DC

Know more about District Cooling

District Cooling is a very mature technology and knowledge is well spread. However it is always good to remind the main factors to consider during design:

  • Proper stimulation of the cooling demand shall be performed to make the proper size of the chillers and thermal energy storage.
  • The selection of the heat rejection method is also important (cooling towers, air-cooled devices, seawater or river water-cooled systems). The simulation will also be helpful to determine the most feasible solution by comparing the energy and water consumption all around the year.
  • Selection of the state-of-the-art equipment: chillers with highest efficiencies, VFDs for pumps, etc.
  • Proper control system with robust equipment to avoid failures and blackouts. Also, the control will be very important to make the plant work with correct efficiency and mitigate the low delta-t problems.

Thermal energy storage is adding many benefits to District Cooling plants: peak load shaving, efficiency increase, plant reliability, and availability increase, etc. This is why most of the new DC is coming with TES.

However, some of the older plants have not TES. It is not too late to add a TES. TES can be added to retrofit DC plants in operation. In fact, in plants that are already in operation, adding a TES system will add another benefit: peak cooling capacity increases.

From a technical point of view, the critical issue is to study the hydraulics of the system. An extra pumping group might be required depending on the case. It is also important to modify the control system so the TES is integrated. Make sure you are with an experienced company.

Efficiency is the key factor of a District Cooling Plant. If the efficiency is not the correct one, then all the investment will result in useless.

There are several ways to improve the efficiency of a District Cooling plant, here you can find the more direct ones:

  • Make proper maintenance. Maintenance and cleaning are crucial for efficiency and correct performance.
  • Retrofit your chillers. Are your chillers more than 10 years old? Chillers are in continuous enhance the process. Retrofitting the plant with new chillers may reduce your energy consumption.
  • Look for integrated energy production. If you are producing cooling with chillers and heating in boilers, try to substitute this for a heat pump which produces cooling and heating with the same primary energy. Have you evaluated a tri-generation option to produce your own electricity?
  • Implement thermal energy storage is best the way to boost efficiency. With thermal energy storage, part of the cooling energy production is transferred from day time (when the temperature is high and chiller efficiency is low) to night time when efficiency is higher. With TES, the overall efficiency all around the year is significantly increased.

District Cooling Plant footprint is always an issue. Most of the DC plants are located in residential areas where the price per square meter is very high. A reduction in footprint is very beneficial.

The layout design and optimization are very important and good improvements have been achieved in the industry for the last years.

However certain technologies can also help to reduce the built-up area. This is the case of geothermal chillers and seawater-cooled chillers.

As these technologies do not require big cooling towers, the design of the system and much more compact reducing the footprint.

Also, no equipment is installed on the roof reducing the built-up area. These give the developers the opportunity of installing the cooling plant in the basement of any building reducing a lot the area impact.

The Control system is the key component for a successful operation of the cooling plant. Therefore, District Cooling Owner should only relay on robust equipment.

It is highly recommended to make an integrated control system, incorporating not only the process equipment but also the control of the Energy Transfer Stations. By having full control of the ETSs from the plant, the operation of the system can be optimized as per the real consumption.

Cogeneration and tri-generation systems are a successful way of integrating the production of different energy types in a single plant and in the most efficient way.

The advantage of these systems is that the amount of wasted energy is reduced to the minimum making the systems to be very efficient and respectful of the environment.

Cogeneration means the production of electricity and heat or cooling energies. Usually, a diesel or gas engine is used to produce electricity. Gas turbines can be used to.

The exhaust heat of the engine/turbine is used to produce heat or sent to an absorption chiller to produce cooling. The system is very efficient because maximizes the use of primary energy.

The concept of tri-generation is quite similar but with the production of electricity heat and cooling. In the case of using a diesel or gas engine, the heat from the engine jacket can be also recovered to maximize the system efficiency.

When compared to traditional standalone chillers definitely it is mainly because of two reasons: higher efficiency and the use of environmentally friendly refrigerants.

Regarding efficiency, District Cooling has demonstrated to be a more efficient solution reducing energy consumption and therefore the carbon emissions and footprint.

Regarding the refrigerants, in the new big cooling plants, the implemented chillers are using the latest generation of Freon refrigerants (R134a, 1233zd) or even natural refrigerants like R717 or R744. Those refrigerants has really low levels of Global Warming Potential (GWP) and Ozone Depletion Potential.

DH

Know more about District Heating

District heating has been continously developing since the decarbonisation objectives have been fixed to reduce the total energy consumption in our cities. However is good to remind ourselves the main factors to succeed on the design phase:

  • Simultaneity study of the network´s heating demand should be performed to select and design properly the generation system.
  • Considering the singularity of building users, will help us design the flow temperature, hourly profile load, and range temperature used in the network.
  • The selection of the most efficient system or combination of technologies should depend on local heat sources, waste heat or heat surplus, and renewable energies available near the network.
  • System optimization with a proper control system can enable high levels of energy efficiency, renewable energy usage and sector coupling.

It is estimated for the Fifth generation that District Heating networks will not use combustion on-site and will have zero emissions of CO2 and NO2. They will employ heat transfer, which uses electricity, and may use heat from renewable energies or remote fossil power stations. The main benefits that they will provide us are:

  • District heating will be a flexible system: decentralized, bi-directional, low flow temperatures.
  • The next generation of district heating  will increase the overall system efficiency by integrating a large variety of supply (CHP, geothermal, heat pump, thermos solar, etc.), renewables energies, thermal energy storage, and demand profiles.
  • District heating will be a more resilient system due to the reduction of dependency on fossil fuels.

Efficiency needs to be the principal vector to set the course toward a more attractive business for all stakeholders (Public and private sectors, end-users, ESCO, contractors, etc.).

  • Use waste heat, heat surplus, or local heat sources close to the District Heating network. 
  • Combine the usage of low-cost electricity and high COP heat generation (heat pumps), with and integrated thermal energy storage (TES).
  • Promote a cooling and heating simultaneity strategy to increase COP and SCOP.
  • Design or redesign the lower flow temperature of the network and increase range temperature saving pumping costs.
  • Promote a circular economy with a flexible grid adapted to the local singularity.

The heat pump technology is effective in District Heating systems, as it captures heat from unlikely sources such as industrial wastewater, groundwater, air and seawater. Recycling heat is particularly impressive because it minimizes carbon dioxide emissions and reduces energy costs.

  • Heat pumps are simply an intermediary between thermal and electrical energy systems, providing the best chance to recover waste heat with very low energy consumption.
  • Heat pump technology use electricity that could be provided by renewable energies such as wind or solar obtaining an optimal combination.
  • All available heat pump technologies  (small, large scale or absorption) are efficient even with low temperature heat source. The combination of geothermal heat source and heat pump combination is one of the most efficient solutions.

The district heating control integration satisfies the communication needs of stakeholders and suits any future modernization needs by providing reliable components.

  • The combination of generation technologies portfolio, different user types and energy cost ratio oscillation force us to simulate several operation scenarios to obtain the best efficiency of the system.
  • Whole system supervision, SCADA, big data and professional analyses will help us learn about the network trends and anticipate the best usage of the different technologies available.
  • A powerful control system allows for network maintainability direct cost reduction and improve end user service feedback.
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