How the SMMS-7 VRF is Designed for the Heat

Engineered for Tropical Comfort

Keeping buildings cool while maintaining occupant comfort and health is no easy feat, especially in Southeast Asia’s tropical climate. In 2018, average recorded temperatures were high year-round in countries such as Malaysia (peak of 35℃ in May), Vietnam (peak of 39℃ in July), Singapore (peak of 35℃ in May), and Thailand (peak of 38℃ in April). Temperatures in the region are projected to rise further potentially by 2-4℃ by the end of the century. Greenhouse gas emissions have been identified as a key contributing factor to global climate change. This makes it all the more important to utilise energy-efficient HVAC systems to reduce carbon footprint.

Southeast Asia has been shaped by tremendous urbanisation and the region includes some of the largest and fastest growing cities in the world. About half of ASEAN inhabitants live in urban areas, and that number is set to grow. Studies have shown that increased urbanisation has a direct impact on urban heat, which is described as the Urban Heat Island effect. According to Cooling Singapore, this effect occurs when an urban landscape is covered with roads, buildings and other paved surfaces; the materials and geometry in this landscape tend to have higher solar radiation absorption and a greater thermal conductivity and capacity for releasing heat stored during the day at night. Reduced vegetation and anthropogenic heat generation are also important factors. One major source of anthropogenic heat is buildings’ reliance on air conditioners that eject heat into their urban surroundings, thus further increasing the importance of selecting energy-efficient air conditioning solutions. In these environments, safeguarding the thermal comfort of building occupants is essential, as studies have shown that indoor air temperature is linked with worker productivity.

The impact of heat stress is further worsened by the high humidity in these countries that often accompanies the rainy season. In high-humidity conditions, the water vapour content in the air impedes the body’s ability to cool itself through perspiration. Sweat does not evaporate as quickly, if at all, when the air is already saturated with vapour. As the body is unable to cool itself in very humid conditions, the heat index – how hot it feels – is often considerably higher than the actual temperature. Several Southeast Asian countries already experience hourly wet bulb globe temperature – the psychological heat strain at high air humidity – of 30℃ or higher during certain times of the year.

Building engineers in Southeast Asia have to make use of HVAC systems that are optimised for cooling in the region’s high levels of heat and humidity. Commercial and residential spaces need air conditioning that is designed to reliably and efficiently beat the heat.

A New Generation of VRF Design

The Toshiba SMMS-7 VRF represents a solution that has been tailored to the hot and humid and weather of Southeast Asia, efficiently enabling building occupants to live and work in comfortable temperatures. The SMMS-7 is the culmination of seven generations of VRF innovation, starting from the Super Multi VRF (1986) and the introduction of key features over the years, such as Intelligent VRF Control and a twin-rotary compressor providing up to 60HP per system.

The SMMS-7 has been designed from the ground up to efficiently and reliably cool commercial and residential buildings in tropical and equatorial weather. The outdoor unit (ODU) has been designed with an expanded operating temperature of up to 52℃ so that it can work reliably over a wider ambient temperature range with extended operation hours. The Toshiba SMMS-7 VRF has a new twin rotary compressor that has been designed with increased core thickness and suction pipe diameter to increase its cooling capacity, and it has a new accumulator design that saves valuable space without sacrificing cooling capacity. Building engineers will appreciate the flexibility afforded by SMMS-7’s smaller compressor footprint and modular outdoor configurability.

The compressor is a vital and expensive component in any air conditioning system. The Toshiba  SMMS-7 VRF compressor is protected by a new oil level management system that detects any drop in oil level and returns oil to the compressor via a unique oil return circuit to prevent downtime or compressor failure. This mechanism ensures that the compressor is always well lubricated, prolonging compressor lifespan.

The heat exchanger is another essential element of the air conditioning system. To provide good heating efficiency, the heat exchanger needs shorter path length and more paths and branches, while good cooling efficiency requires the opposite. In the past, air conditioning systems had to be designed for a balance between heating efficiency and cooling efficiency. With its total focus on delivering the best cooling efficiency, the heat exchanger of the SMMS-7 VRF is longer with fewer paths and branches.

Made with Efficiency and Environment in Mind

Toshiba’s Intelligent VRF Control ensures the system provides consistent cooling only where and when it is needed, handling the cooling needs of different kinds of loads. This is particularly important in part-load situations. While conditions of optimal thermal comfort can improve performance, individual control over room temperature is also important. However, when the different indoor units (IDU) are adjusted to cater to differing occupant requirements, these varying loads can be a challenge to cool efficiently. SMMS-7 VRF optimises system efficiency to handle this challenge, with each IDU being able to vary the volume of refrigerant independently at a constant rate, so there is no wasteful on-off cycling.

With its improved full load and part-load efficiency, SMMS-7 VRF is able to reduce energy consumption by up to 20%, thus minimising its environmental impact. In addition, the new liquid pipe temperature control algorithm and tankless design of the SMMS-7 reduces refrigerant use by 30%.

The Toshiba SMMS-7 VRF has been created to do the job of cooling built structures especially well in the Southeast Asian heat. With reliable cooling capability, a smaller footprint, smart controls to handle varying loads, and environment-friendly efficiency, it is the ideal system for the challenging climate in the region.

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