INDIA: Leading air conditioning companies Daikin and Gree are among eight finalists for the Global Cooling Prize, the international innovation competition to develop super-efficient and climate-friendly residential cooling solutions.
The $3m initiative, launched last year with backing from British entrepreneur Sir Richard Branson, is a two-year competition to find a residential cooling technology with at least five times less climate impact than standard room air conditioning units.
The competitors showcased technologies that reduce or eliminate refrigerants linked to climate change, advances that will be vital as the number of room air conditioners nearly quadruples by 2050.
The eight teams selected pitched a wide range of technologies, including smart hybrid vapour compression designs, evaporative cooling systems, and solid-state cooling technologies.
The Daikin concept involves an air conditioner using the low GWP HFO refrigerant R1234ze(E), utilising the heat of vaporisation to lower the temperature of the air that the outdoor unit takes in. Gree’s solution is a hybrid of vapour compression refrigeration, direct evaporative cooling, and ventilation.
Sir Richard Branson, founder and CEO of the Virgin Group and the prize’s global ambassador, said the competition had attracted “some absolutely revolutionary cooling ideas”.
“What makes this competition especially exciting, is the market transformation opportunity,” he said. It could be one of the biggest technology-based steps we can take to arrest climate change.”
The Global Cooling Prize was launched in November 2018 by a global coalition led by the Department of Science and Technology, Government of India; Rocky Mountain Institute (RMI) — a leading global research institute; and Mission Innovation — a global initiative of 24 countries and the European Union to accelerate global clean energy innovation.The initiative is also supported by Conservation X Labs, Alliance for an Energy Efficient Economy (AEEE), and CEPT University, and a coalition of over 20 leading international non-profit organisations.
The winner of the Global Cooling Prize will be announced in November 2020.
Daikin Industries and its subsidiary Daikin Air Conditioning India worked with Nikken Sekkei, one of the leading Japanese architecture and engineering design companies to develop a system using two innovative methods to achieve a higher efficiency and lower climate impact cooling solution.
According to Daikin, this new concept employs a technology which can achieve comfort and energy savings and, at the same time, ensure consistent room temperature and humidity by controlling multiple indoor units in one room. The system measures the outdoor temperature and automatically sprays water under high ambient temperature conditions, to lower the temperature of the air that the outdoor unit takes in.
Daikin adopted an out of the box approach by controlling multiple units in one room and by choosing the low GWP refrigerant R1234ze(E)．
However, Daikin admits that the use of this lower capacity refrigerant causes other environmental challenges such as the increased use of raw materials as a result of the necessary larger equipment size.
Daikin insists its overall refrigerant policy is to support a diversity of refrigerants and believes that R32 “is the most balanced refrigerant for many applications” in terms of safety, energy efficiency, economy and the environment, and that it will be “the standard for the mid- to long-term horizon”.
“Daikin believes that reducing the environmental impact of room air conditioners can only be achieved by disseminating equipment with the best possible efficiency and low environmental impact throughout the lifecycle of all equipment all over the world,” the Japanese manufacturer said in a statement. “Daikin continues to work on the quest of new refrigerants and equipment taking into account safety, energy efficiency, climate change, and affordability, and this proposal is part of that research initiative.”
Stressing that R32-based equipment is an established technology, being sold in more than 70 countries including India, it continued: “Daikin’s participation in the Global Cooling Prize is consistent with our “Environmental Vision 2050” which provides a roadmap for the company to carbon neutrality by 2050. In line with that vision, Daikin is in a continuous search to reduce energy consumption and refrigerant impact. Our participation in the GCP is a part of that effort to examine energy efficiency technology with low GWP refrigerant alternatives.”
Chinese air conditioning manufacturer Gree collaborated with Tsinghua University, one of the top universities in engineering field in the world, to develop what it describes as a super-efficient and climate-smart residential cooling solution.
The hybrid solution uses vapour compression refrigeration, direct evaporative cooling, and ventilation, automatically switching between modes or operating the three modes in parallel depending on the outside weather conditions. The vapour compression mode is said to employ an innovative temperature-humidity-independent-control cycle. It also employs a new design of compressor with a low GWP refrigerant improved evaporator and condenser systems to more effectively cool and dehumidify the air.
The solution also has a small solar PV panel integrated into the outdoor unit.
Godrej and Boyce
Godrej and Boyce partnered with a fellow Indian company and leading evaporative cooling technology company, ATE Enterprises, to develop what it describes as an advanced hybrid cooling technology built on its established use of propane as a refrigerant.
The evaporative cooling technology employed is designed to reduce the air temperature without adding to its humidity level. This cool air is then either supplied directly to the indoor space or passes through the vapour compression system which optimises compressor performance depending on the desired indoor temperature and humidity.
Like Gree, the Godrej solution also employs an integrated solar PV panel.
Barocal Ltd is a new British start-up established by William Averdieck to pioneer and commercialise barocaloric cooling and refrigeration technology. Working with co-founder Dr Xavier Moya, Barocal’s cooling system originates in part from Moya’s research at the Materials Science Department at the University of Cambridge.
This solid-state technology takes advantage of the properties of solid organic “plastic crystal” materials to provide the cooling. By applying pressure to these organic solid crystals, it is possible to change their molecular orientation which results in a solid state phase transition, thus causing a change in their entropy, which leads to a temperature change of the system. The process of continuously “applying and releasing pressure” on the Barocaloric material results in solid-to-solid phase changes in the crystals which results in large thermal changes due to molecular reconfiguration. This produces a cooling effect which can be delivered either to the room air or to produce chilled water for cooling.
These plastic crystals are flexible materials that are said to be widely available, low-cost and non-toxic.
US chemical company Kraton Corporation is collaborating with Indian IT consultancy Infosys, the Indian Institute of Technology Bombay, and Indian chemical company Porus Labs to develop another hybrid cooling solution. This one uses NexarCool Technology, a membrane dehumidification system based on Kraton’s Nexar polymer.
NexarCool technology integrates what is called an electro-osmotic membrane dehumidifier with a water-based direct evaporative cooling system. By applying a small voltage across the membrane dehumidifier system, water vapour from the indoor air is ejected to the outside air, thus making the indoor air dry in the process. The dry indoor air is then cooled via a direct evaporative cooling process.
M2 Thermal Solutions
M2 Thermal Solutions, a startup company based out of the United States, is developing a cooling solution that uses a combination of evaporative cooler and membrane technologies to independently cool and remove moisture from room air.
In this system, an evaporative cooler first operates to cool the room air while increasing its humidity. The cool and humid air is then passed through a membrane system to remove the excess water vapour from the cool air, thus decreasing its humidity. The solution also has the capability to bypass either of these processes, and just use a ventilation mode depending on the outdoor weather conditions. Furthermore, the vast majority of the water supplied to the evaporative cooler is generated by the membrane system – thus minimising its water footprint.
S&S Design Startup Solution
A group of Indian mechanical engineering researchers and innovators with expertise in air conditioning design and development are developing a hybrid residential cooling solution combining a two-stage cooling system with direct evaporative cooling of the condenser to achieve a significantly higher efficiency.
The system integrates a water loop and a traditional vapour compression system to optimise the performance. The water loop pre-cools the room air which is subsequently cooled and dehumidified to the desired conditions at the evaporator of the vapour compression system. At the condenser section, a part of this conditioned air is further cooled using direct evaporative cooling.
The performance is further optimised by using a variable speed compressor and a “natural” refrigerant.
Transaera Inc, a manufacturing startup out of the Massachusetts Institute of Technology (MIT), USA, is developing a hybrid cooling solution with desiccant dehumidification technology based on novel materials discovered at MIT to solve the cooling challenge.
The cooling solution is designed to operate a high efficiency room air conditioner in parallel with a moisture storage battery to provide cooling and dehumidification while using dramatically less energy than typical room air conditioners sold today.
By separating the temperature and humidity control processes, this air conditioner is claimed to have the potential to reduce the energy consumption significantly while providing the desired comfort level.
Transaera’s moisture storage battery comprises a novel desiccant material, with the capacity to adsorb a large amount of moisture allowing room air to dehumidify. Dry air is easier to cool with the high efficiency AC unit, thus reducing the overall electricity consumption. Additionally, while typical desiccant materials require a high-temperature source for regeneration, the MSB material is said to be able to regenerate using waste heat from the vapour compression system.
The system also has a provision for direct evaporative cooling of air at the condenser inlet to improve condensing efficiency, a small integrated solar PV panel and battery to reduce grid-consumption and the ability to collect rainwater for use to improve the overall environmental impact of the solution.
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