Applying an Intelligent High Efficiency Energy Recovery System

Sean Convery, Cator, Ruma & Associates
Mark Labac, Edge Mechanical Systems, Inc.

The University of Colorado Boulder Sustainability, Energy and Environment Complex (SEEC) implemented a Konvekta Intelligent High Efficiency Heat Recovery System with MeeFog Evaporative Cooling.

Labs typically use Run-Around Loops, Energy Recovery Wheels, Refrigerant Heat Pipes or Plate Heat Exchangers. Run-Around Loops are flexible by allowing the supply air to be remote from the exhaust air; however, are less efficient. Energy Recovery Wheels have a high thermal efficiency; however, require the supply and exhaust air to be adjacent and bypasses some exhaust to the supply. Heat Pipes have a high thermal efficiency; however, require supply and exhaust air to be adjacent and may have too much refrigerant for enhanced refrigerant points in LEED. Plate Heat Exchangers also require the supply and exhaust air streams to be adjacent, have a high pressure drop and are difficult to clean.

An Intelligent High Efficiency Energy Recovery System is similar to a run-around loop; however, uses strategies that makes it more efficient than other systems. This system uses special coils with a high water pressure drop to keep turbulent flow through a wide range of flow rates, allowing a variable flow system. This system uses lower gpm compared to a run-around loop resulting in similar pump horsepower. A single coil in the air handler performs energy recovery, preheat and cooling by using one piping system with the correct temperature water needed to achieve the required air temperature. Eliminating the heating and cooling coils provides an air pressure drop reduction. The pump skid has heat exchangers to optimize the temperatures of the recovery loop. The pump skid has a control system that monitors supply and exhaust temperatures, heat recovery temperatures, and chilled and heating water temperatures to optimize the energy recovery water temperature, pump speed, and control valve operation. This system performs a numerical simulation once per second using 3D performance maps of coils, pumps and valves. Using evaporative cooling in the exhaust can increase the summer efficiency in Colorado by another 40%. The manufacturer of this system, Konvekta, offers a financial guarantee on the annual energy savings of this system.

Since this is an expensive system, it is imperative to review cost reductions of other systems to bring into cost neutrality for most projects. The preheat and cooling coils are removed allowing the air handlers to be reduced in size, removes controls, coil piping, coil pumps, and 2 piping systems to these air handlers. For the University of Colorado SEEC project, there was also a heat recovery heat pump removed. Another large cost savings is the reduction in pipe size for the energy recovery loop.

Learning Objectives

  • Identify the conventional Heat Recovery Systems used in Laboratories along with their benefits and drawbacks.
  • Description of an Intelligent High Efficiency Heat Recovery System and its benefits.
  • Applying an Intelligent High Efficiency Heat Recovery System while keeping it cost neutral.

Biographies:

Sean T. Convery, PE is a Mechanical Principal at Cator, Ruma & Associates in Denver, CO. His 19 years of mechanical design experience include energy-efficient mechanical systems for higher education campuses and research labs. Recent projects include the University of Colorado Boulder's Sustainability, Energy and Environment Complex (LEED Gold Pending), Biotechnology Building (LEED Platinum), and Colorado State University's Suzanne and Walter Scott, Jr. Bioengineering Building (LEED Gold).

Mark Labac, PE is the president of Edge Mechanical Systems, Inc., a specialty Heating Ventilation and Air Conditioning Manufacturer's Representative firm in Colorado. The firm specializes in energy efficient equipment with a focus on the laboratory industry and LEED projects. The firm represents manufacturers serving the laboratory industry, which include Air Flow Equipment, Konvekta, MeeFog, M.K. Plastics, and Spunstrand.

 

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