In an ATMOsphere America 2014 session sponsored and moderated by leading biotechnology company Genentech, Conservation Mechanical Systems and Munters des Champs presented projects focused on using water to provide cooling in HVAC applications. The case studies covered a variety of topics, including benefits of the use of evaporative cooling, challenges for the industry, future trends, and more. According to Genentech, they are making between $350 and $600 million available for investment in natural refrigerant technologies for the planned upgrade of their campus HVAC&R systems.

The 3^rd annual ATMOsphere America, which took place in San Francisco, California from 18 -19 June, featured a conference series first: a session dedicated to HVAC, giving participants the opportunity to share experiences and knowledge on natural refrigerant uses in a new application area.

Absorption chillers using water as a refrigerant for 36-building campus HVAC system

Michael Morehead, Global Engineering, Mechanical Engineer at Genentech, presented a technology case study of a planned campus conversion to natural refrigerants, pointing out the potential economic benefits of such a project given pending the US HCFC and HFC phase out and phase down. The campus in question has 36 buildings and over 650 pieces of equipment including:

• 47 large units of over 100 tons
• 618 mid size units of below 100 tons
• 3,533 small units of fractional ton capacity

In addition to cold rooms, process cooling chillers, and large central chillers, Genentech relies on specialty equipment such as -80°C freezers and lyophilizes. Each application will require a different natural refrigerant technology. Whilst hydrocarbons could be used for the lyophilizers and process cooling chillers, and CO₂ for the walk-in cold rooms and freezers, absorption chillers using water as a refrigerant could be used to replace the large central chillers. Genentech is also interested in the results of pilot R718 turbo chiller projects.

Morehead challenged the natural refrigerant industry to provide Genentech with solutions, by:

• Improving packaged CO₂ transcritical units,
• Developing CO₂ systems for the HVC market
• Educating fire Marshalls about hydrocarbon refrigerant equipment
• Marketing hydrocarbon chillers in the US and developing a service network

Reduction in peak electrical demand of 20 to 30% thanks to UFAD and evaporative cooling

During his presentation, Mike Scofield, President of Conservation Mechanical Systems showed the difference between conventional overhead air distribution systems and Under Floor Air Delivery (UFAD) designs for air distribution, and discussed the benefits of the UFAD system on Indoor Air Quality (IAQ) as well as the marriage of this concept to a two stage evaporative cooling system. According to Scofield, as well as providing economic benefits the UFAD system reduces fan energy, increases free cooling economizer hours, and allows personalized climate control for occupants.

Scofield presented two case studies featuring the technology; one at the Dona Spring Animal Shelter project, where a two stage evaporative cooling design was used with an overhead delivery system to eliminate mechanical cooling, and a retrofit project of a 100 year-old building, using a direct evaporative cooling system combined with a UFAD design. According to Scofield, the benefits of evaporative cooling include a reduction in peak electrical demand of 20 to 30% compared to refrigeration design with air-cooled condensing system.

EPX Heat Exchanger Technology for Dry Evaporative Cooling

Vijayanand Periannan, Regional Sales Manager Munters des Champs shared his experience on EPX heat exchanger technology for dry evaporative cooling. He argues that because evaporative cooling humidifies and cools, providing a constant wet bulb temperature, in warm weather a combined indirect and direct evaporative cooling (IDEC) system requires less refrigeration cooling than a 100% recirculation system. What is more, it provides better inside air quality, reduces energy costs and allows for a reduction of 29% in refrigeration load over 100% recirculation.

Periannan presented an annual energy consumption comparison of a 100% outdoor air IDEC variable air volume (VAV) system with a 25% outdoor air economizer VAV system in Sacramento. The IDEC design resulted in a significant reduction in peak demand charges and further peak KW reductions if combined with TES.