District Cooling System is the future'

Benjamin Samuel,
General Manager and Head,
Building and Construction Division,
Kirloskar Brothers Ltd.

Satish Purohit interviews Benjamin Samuel, General Manager and Head, Building and Construction Division, Kirloskar Brothers Ltd., on the company's latest innovations in plumbing, waste management, and HVAC solutions.

What challenges do you see emerging on the horizon as a solutions provider due to the fact that buildings are going increasingly vertical?

In terms of high-rise buildings, I don't see much of a challenge or changes but if you talk about smart cities or smart solutions, district cooling is something that is likely to develop in a big way. This is mainly in terms of HVAC. We already have a system in place in GIFT City, Gujarat. In many of the Middle East and European countries, the concept is a commonplace. It involves a central cooling plant that provides chilled water to buildings in the vicinity or whoever the customers are and there is only heat transfer that takes place at the user end, who uses the chilled water for HVAC needs. The practice of having a separate HVAC or chiller plant for separate buildings is likely to become obsolete in the future. Like electricity, where every individual is metered as per his or her consumption, chilled water will similarly be metered in future. This is something that has not caught up in India but I believe this would soon be widely accepted. In high-rise buildings,there is basically a problem of fire-fighting, which is a major issue as the fire department is not well-equipped to serve as per the expected requirement asits equipment has certain limitations in terms of height upto which it can reach. The internal fire-fighting equipment within a building that includes the fire detection or suppression systems hasto be quite strong for the fire personnel to be able to douse any level of fire.

What is the nature of your service? Are there components of AMC as well?

We don't do the installation ourselves. Generally, it is done by the fire contractors and, in case of HVAC,it is done by OEMs. After the warranty period, we take AMCs for the fire-fighting or plumbing  or HVACpumps and ensure that they are in running condition throughout the year.

Could you tell us something about your dewatering pumps?

Dewatering pumps are basically of two types. Normal dewatering pumps are used in societies or complexes where water gets accumulated . Theother bigger pumps called 'Auto prime' are used for de-flooding applications,. Many cities witness heavy downpoursduring the monsoons and there is lot of flooding along roads, railway tracks and buildings . In such situations, these heavy-duty pumps automatically perform self-priming wherever the water level rises. Any centrifugal pump has to be primed before it is started; i.e. in the outlet you have to fill water or create a vacuum. However,such pumps have an inbuilt priming systemthat starts automatically as soon as you switch on the pumpfacilitating the removal ofhuge amount of water. These pumps have been extensively used during the floods in Kerala last year. They were also used for dewatering purposes during the floods in Jammu and Kashmir as well as atDelhi and Kolkata airports.

Could you share insight on technology and innovations that may become part of the Indian high-rise landscape.

We have already introduced the Multi-StageMulti-Outlet pumps in India. These are basically developed for firefighting applications in high-rise buildings. Generally, for firefighting applications, buildings are divided into zones. Each zone requires a certain pressure; you cannot allocatethe same pressure level for the entire building. Either you need to use pressure reducing valves or you need to have multiple pumps. To facilitate the same, we have developed a single pump that has multiple outlets. Each outlet delivers water at different pressure level. In each zone, depending on the height of the building,you have different pressure level. In the US, where there are set norms for such applications, we already have gained the necessary approvals. India is yet to draft standardised norms in this area but it is just a matter of time before buildingcodes are standardised and consultants arrive at a consensus.

Could you elaborate on the dangers posed by the use of submersible pumps in case offirefighting?

For any firefighting application, most of the standards call for the electrical parts to be above water and not submerged. In case of a submersible pump, these parts remain submerged. This is the first risk. Secondly, these pumps are located within the tank and are not visible and one cannot know whether the pump is functioning properly or gauge symptoms of breakdown. If it is a surface pump in a pump room, it is very easy to monitor. In case of a submersible pump, if it has to be serviced, you are required to empty the tank first to remove the pumpand it has to be taken to some service centre as,most of the time,these pumps cannot be serviced on-site. All this is a time-consuming activity. Having a surface pump is therefore more viable in such cases.  Moreover the submersible pumps don't conform to hydraulic performance over their entire range of operation as required by fire standards.

What elements in your opinion should be included in the overall building design to ensure better fire safety?

First of all, in a pump room, it is very important to have sufficient space to carry out maintenance activities. Most pump rooms are designed in such a way that, if you remove the motor or engine or the pump, then there is no space to manoeuvreor even take the pump outside. Secondly, this may not be mandatory but I would suggest pressure gauges to be installed along with the flow meters. I would also recommend an annual audit of the system and check if the pumps are performing. In industries, you have norms. Most MNCs conducttests every year and they plot the graph to check if the pump is performing properly or not. In any pump, over the years, there is going to be degradation inperformance due to mechanical wear and tear. This annual testhelpsone to ascertain whether the pump requires maintenance or some kind of preventive maintenance or replacement.

Could you explain how chilled water is used to cool spaces with the district cooling models?

District cooling system (DCS) distributes thermal energy in the form of chilled water from a central source to multiple buildings through a network of underground pipes for use in comfort cooling. The cooling or heat rejection is usually provided from a central cooling plant, thus eliminating the need for separate systems in individual buildings.The central plant generates chilled water withchillers. Large size centrifugal chillers with higher efficiency are usually installed to take advantage of the economies of scale.

At the receiver or consumer end (building) heat exchangers are installed which exchange thermal energy between DCS chilled water and building chilled water.

Chilled water available from DCS is much more economical than owning and operating a chiller plant. The consumer also does not have to worry about maintenance of the plant. Besides, by not having a chiller plant in your own premises, you save space which can be used more effectively.

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