IIT Delhi innovates AC technology to reduce electricity consumption by 33%

Scientists at the Department of Mechanical Engineering, IIT Delhi, are working on a new type of high, efficient air conditioner that has already demonstrated a capacity to cut electricity consumption by about one third.

It is known that rapidly increasing heat stress leads to various health risks and lowers productivity, and these effects have already reached alarming levels. According to the India Cooling Action Plan, Report by Ministry of Environment, Forest and Climate Change, Government of India, 2019, with the increase in temperature and the consequent rise in air conditioning usage in homes and offices, electricity consumption for cooling will be three times more by 2037, 38.

The researchers are also in the process of developing a different type of energy, saving air conditioners to solve the problem.

The group of researchers led by Prof Anurag Goyal and including Ananthakrishnan K, a doctoral research student of the Department of Mechanical Engineering, is currently developing a laboratory- scale prototype of this new system, which has already demonstrated a capacity to reduce electricity consumption by approximately one third.

The vapor-compression system-based ACs in use today remove humidity by overcooling the air until moisture condenses, which is a highly energy-intensive process. Prof Anurag Goyal's research group has developed a new concept that utilizes a compact add-on module to directly tackle moisture.

The module uses a salt solution (liquid desiccant) that absorbs water vapor from incoming outdoor air. A thin and selective polymer membrane sits between the air and the salt solution and prevents the salt from carrying over into the building's air, which is a common concern with existing liquid-desiccant systems.

After the solution is diluted by absorbed moisture, it must be dried to allow continuous reuse. The team uses an innovative system integration concept to continuously revive and recirculate the same salt solution. Instead of adding a burner or an electric heater, the design uses heat that the AC already throws away through its condenser (the outdoor unit) and redirects it to a regenerator module to dry the salt solution again.

The system is designed to precisely match the energy transfer rate in the two parts, vapor compression and desiccant modules, across various outdoor cor the hybrid, resulting in around 33 per cent lower energy consumption, while meeting the same indoor comfort targets. Across representative Indian climates, the predicted savings range from 28 per cent (in very humid areas) to 41.5 per cent (in dry and arid areas)," Prof Anurag Goyal said.

The research team anticipates wider adoption of such a sustainable cooling technology, particularly in Indian buildings.

A study titled 'Model-based analysis of a novel hybrid membrane-liquid desiccant air conditioner for high-efficiency space cooling' on their work has been published in the Journal of Building Engineering.