Designing, operating & maintaining it right

Air-conditioners, which was once considered a luxury, is now being used in almost every households and commercial spaces. However, proper maintenance of the system is something that is being ignored in most situations. Here, industry experts discuss the growth of air-conditioning systems and need for proper operation and maintenance of the system.

Developments in system design
Design is one of the important aspectsof an HVAC&R system. Several concepts are being used in different scenarios depending on the system and the environment.

Sangita Jhangiani, Consulting Engineer, Founder, Enova and President, Mumbai Chapter, Indian Society of Heating, Refrigerating and Air-Conditioning Engineers (ISHRAE), says that design of a system is very important. “Thermal performance of a building is one of the most important things. Our country is in the northern hemisphere. If the glazing is on the west or the south, it increases the thermal load on the building. So we guide the architect to orient the building or put the glazing on the north side, which would help in letting less thermal load into the space,” she adds.

As we know, air quality has taken a backseat in our country, and the government is focusing on reducing pollution. “Air needs to be filtered before it enters the building. Some years back, one of the things people were doing to reduce the energy was to provide less outdoor air inside the space or room. Lot of work is being done in that area,” says Jhangiani. Indoor air is cooler than the air present outdoor. “So when you take in the outside air, the load on any air-conditioning system just goes up. Therefore, it is necessary to introduce concepts on how to pre cool without electrical power. Heat recovery is one concept. So there are similar other concepts, which are now accepted and now designers are using those,” she adds.

Rise of water-cooled systems
Sewage Treatment Plant (STP)has been made mandatory for commercial and residential projects by the government. Jhangiani explains, “Earlier, people were not getting enough water for cooling purposes. And to remove heat from an air-conditioning unit, water is required. Thirty years ago water was available everywhere. But later on, there was water crisis. So people were not getting enough water for air-conditioning. As the demand of air-conditioner started growing in the country, water-cooled systems took a backseat, although it consumed less power. Despite the fact that they consume lesser power, they were difficult to sell in the market because of non-availability of water.”

Now, because of STP, we have waste water available for cooling purposes. Now, water-cooled systems are being preferred as compared to air-cooled systems, which consume 25-30 per cent more energy. So that is one of the good things that has happened, she adds.

Designing energy efficient systems
There are two major agencies that make regulations and technical parameters for HVAC&R systems: American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) at global level and ISHRAE in India. Kulwant Singh, Entrepreneur and Founder, Kleanwave Solutions says, “As per demand of market and technological evolution, the standards are raised a bar to meet the specific needs.”

The basic parameters for designing energy efficient HVAC system are as follows:
1.Proper and accurate heat load calculation: Heat load calculation is the base of any HVAC system. Whatever technology (water cooled chillers, air cooled chillers, VRF, Package unit etc.) being implemented for a HVAC system shall be designed and selected on the basis of heat load only.
2.Selection of energy efficient products having low carbon foot print.
3.Designing best and efficient air distribution system.
4.Including new technologies like using Ultra Violet Germicidal Irradiation (UVGI), electrostatic filtration etc. to improve products efficiency by reducing consumption at AHU coil and filtration level, which also leads to improved indoor air quality.

Singh suggests that the above parameters are not enough to make HVAC system energy efficient; more energy can be saved if the designing work starts from the civil and architectural level hence Indian Green Building Council (IGBC) ensures that a building will be green building if meets the standards made to qualify for it.

Maintenance and best practices
Aditya Mittal, COO, Mittal Refrigeration explains that good service practices start from day one when an air-conditioner, refrigerator or a cold storage is installed. He suggests, “Initially, after installation, the copper tubing should be vacuumed properly; deep vacuum is very important. Charging the right refrigerant and using the proper heavy gauge copper tubes, proper brazing alloys, proper insulation, etc. are very important.”

Talking about service practices, he suggests that bi-annual maintenance is very important. “Bi-annually the cold storage, air-conditioner, heat exchangers, condensers, and cooling coils should be cleaned; wet service is the correct way of cleaning them. This is a mandatory procedure, but people do not do it. And, you should be getting it done through a qualified technician or engineer. If the heat exchangers are cleaned properly, then there will be less load on your compressor and simultaneously you will be saving more energy.”

However, Mittal raises a concern that good tools and equipment are equally important, which, unfortunately, are not used in our trade. “Refrigerant is a chemical or gas and people do not use a leak detector to find the leakage. Some people do not know about leak detectors and some don’t want to spend money on it. Another practice is using recovery machine. If you are moving your air-conditioner or cold storage, the gas should not be left out in the environment, and if leaked,it should be sucked back and stored in a cylinder.For that, a recovery machine is required. Just like leak detectors, people do not invest in a recovery machine.”He suggests that the mind set has to be changed and good service practices are required.

Training of service personnel
A trained workforce is the need of the hour, says Mittal.Since India has signed the Paris Agreement, we are also part of the Kigali Amendment. The government is, thus, very much committed towards saving the environment. We are already moving from HCFC refrigerants towards HFC.

“A move to HC (Hydro Carbon) refrigerants, is not yet recommended for our industries and consumers, as these refrigerants are flammable,” he adds. In every household, people are using LPG or kerosene, which is flammable. However, people are not ready to accept the fact that every refrigerator and air-conditioner has a flammable refrigerant. So, you need good engineers, qualified technicians, who will do quality service practices, and better installation so that no fire hazard occurs.

Generating customers’ awareness and training technicians are major concerns that needs to be addressed. “Though there is an increase in growing demand for cold storages and air conditioners, we are falling short of people ready to be a part of this sector and the already working technicians lack the skill and are waiting for the right opportunity to upgrade themselves,” Mittal concludes.

As per demand of market and technological evolution, the standards are raised a bar to meet the specific needs
Kulwant Singh, Entrepreneur and Founder, Kleanwave Solutions

‘A trained workforce is the need of the hour’
Aditya Mittal, COO, Mittal Refrigeration

‘Now, because of STP, we have waste water available for cooling purposes’
Sangita Jhangiani, Consulting Engineer, Founder, Enova and President, Mumbai Chapter, ISHRAE