Just imagine this scenario that you are out there in the field or inside a building with the sweltering heat that you no longer can bear it anymore feeling like it is the hottest day on planet Earth since the dawn of civilisation. But one thing for sure that keeps you going is that in your mind you will be in your air conditioned home or office say in an hour. Then, that moment came when you opened the door and step into your home or office, there you start feeling the gust of cooling air enveloping every cells of your body which instantaneously make you felt better.
Certainly, the ‘cooling revolution’ of air conditioners that has been brought to the human society soon after the air conditioner technologies was discovered can never be discounted though the previous generations had only fans or other ways of keeping cool during the hot days, they were not as amazingly effective or efficient as the modern days air conditioners, particularly on its sheer cooling capacity and the cost of its operations.
Before we explore further, let us understand more about air conditioners. In an air conditioning system, there is a process whereby the heat from the return air (warm or hot) and moisture from the interior of the occupied space such as rooms or building is removed to bring comfort to the occupants and this process is used in achieving more comfortable interior environment. However, at the same time the air conditioners not only provide cooling air into such environment but also to cool off or dehumidify the rooms filled with electronic devices that generate heat, such as computer servers, power amplifiers, etc.
Air conditioners commonly use a fan system to distribute the conditioned air to the occupied spaces as in buildings or an automobile for the improvement of its thermal comfort as well as its indoor air quality. Refrigerant-based air conditioners that ranges from a small capacity unit for cooling a small bedroom which such unit can be practically hand-carried by an adult and up to massive capacity units that are installed on the rooftops of office towers for cooling the entire building.
In short, air conditioning system refers to any form of technology which modifies the condition of the surrounding air either by heating, humidification/dehumidification, cleaning, cooling, ventilation or air movement and such system generates cooling air to its enclosed environment at the temperature and relative humidity that can be set to the desired level in achieving the most comfortable environment. Based on the working principles of an air conditioner, the evaporator coil (heat exchanger coil) collects the return air (heat) from the occupied spaces (rooms/building), processes it through a refrigerant gas, then, releases the cool air into the occupied spaces where the return air (hot) had originally been collected. The evaporator coil not only absorbs heat from the return air but also wrings out the moisture in the incoming air and this works out to dehumidify the occupied spaces. Hence, the air conditioner cooling the rooms/building or transport space with the cold evaporator coil (indoor unit), followed by the condenser (hot coil in outdoor unit) releasing the heat that was collected from outside. These coils (condenser and evaporator) are tubing in serpent-like winding shape that is surrounded by fins made of aluminium, then, the pump (compressor) transfers the heated refrigerant in its fluid state between the condenser and evaporator coils pushes the refrigerant through its circuit of fins and copper tubing in the coils, so the refrigerant in the liquid state evaporates within the evaporator coil, taking the heat out of the air in the indoor and hence cools down the office/home, whilst the refrigerant in the state of hot gas is pumped out into the condenser (outdoor unit) which then changes back into liquid transferring the heat to the flowing air to the fins and tubing of the condenser. Basically, this is the way the air conditioner works.
Cooling environment has become a fast increasing demand, especially amongst the developing countries, hence warrants the building design in reducing the cooling loadings as well as the efficiency of the air conditioners has to be improved. The good news is that the efficiency of the best available technologies in air conditioners today is deemed higher than the average of installed efficiencies with further offering on its scope in savings on carbon dioxide (CO2) emissions.
In every air conditioner, there is a rating that measures its energy efficiency and this rating represents the amount of BTUs (British Thermal Units) for every hour i.e. BTU per hour (BTU/h) that is removed from the occupied space for each wattage of power that it had drawn. By the way, this rating of energy efficiency for room air conditioners is referred to as Energy-Efficiency Ratio (EER), whilst central air conditioners it is termed as Seasonal Energy-Efficiency Ratio (SEER) and according to EnergyStar (voluntary program launched by the US Environmental Protection Agency (EPA)), appliances including air conditioners labelled with EnergyStar will have high ratings of SEER and EER. This means the EER is a measure of how efficient is a given cooling system operates whenever the temperature of its outdoor is at a specific 35°C. Normally, the higher is the value of the EER, the more efficient is the air conditioning system. In an air conditioning system, generally it falls under substantial energy users and these likely increases the running costs of a building by as much as 50%.
Currently, air conditioners in the energy efficient category consume around 30% – 50% much lesser energy generating similar amount of coolness as those air conditioners that were made in the year of 70’s. It does not matter how old is the air conditioning system but about 20%-40% of the costs for its cooling energy is able to be saved simply by replacing the unit with a much newer energy-efficient air conditioner model. Furthermore, if the high efficiency electrical appliances are being used, then, the savings will increase further as a result of the reduction in electricity demand for the air conditioners, particularly in commercial buildings.
In the United States, a few researches are ongoing since 2017 with some really interesting new air conditioner technologies in moving forward towards developing a far greater reduction in its energy consumption. From this innovation and creativity activities, it would enable us to not only find ways to overcome the heat in the occupied spaces but also at the same time have some monetary savings in terms of our energy bills.
The following are the 5 cooling projects being currently developed by the respective researchers in the advancement of technologies in air conditioners:
- To develop an advanced technology heat exchanger in the air conditioner (evaporator coil) unit that minimises joints by about 90% as compared to the existing models in reducing the refrigerant leakages. Once the joints are minimised, the refrigerant will stay on at the place where it is supposed to be, thus, it works to make your home cooling with the energy bills gets much lower.
- To develop a prototype model that combines the water heater, air cooler and dehumidifier to produce a more efficiency transfer of heat within its coils and this technology enables to enhance the control on its dehumidification process in the residential buildings that will provide much better comfortability and more savings in its energy bills.
- To develop new membrane based air conditioners, particularly the rooftop air conditioners that utilises water instead of the conventional chemical refrigerants. This new technology not only is ideal for the sweltering nights and days but also it will have lots of savings with as much as 30% – 50% of its electrical consumption as compared to the rooftop air conditioners found today, especially in commercial buildings.
- To explore in electro caloric and solid state technology in developing a heat pump compressor (vapour compressor) which will make an occupied space cooling without utilising chemical refrigerants. Such technology will be perfect for small scale commercial building or residential premises as it will be built to much smaller size and operating quietly which would result in around 25% improvement in its system efficiency. Due to its lesser mechanical parts involved, thus, providing improvement in its overall reliability, thereby increasing your chances to continue to have the air conditioner working perfectly, especially during the seasonal heat wave!
- To develop a system for energy-storage, integrating it with the HVAC (heat, ventilation and air conditioning) system, whilst reducing the overall energy that is required by the air conditioning system as a result of its utilisation of the heat-waste which otherwise would have been lost as in the conventional system. From the integration of the diverse ground level energy-storage system with the HVAC system, it is able to achieve the overall energy-storage system efficiency by some 70%, whilst at the same time improving the HVAC system performance by as much as 35%.
We wait in eagerness for the successful achievement in the above 5 projects relating to the advancement in the air conditioner technologies that would be realised commercially in the not too distant future.