Design, Installation, and Field Verification of Integrated Active Desiccant Hybrid Rooftop Systems Combined with a Natural Gas Driven Cogeneration Package

This report summarizes a research/demonstration project in which a new high school facility was designed and constructed to combine a custom built 230 kW cogeneration package with four integrated active desiccant rooftop (IADR) systems to serve as high-efficiency dedicated outdoor air systems (DOAS). The IADR systems were modified to include hot water coils to use the waste heat provided by the engine jacket water for desiccant regeneration during the peak cooling season and heating during peak heating conditions. Each IADR was coupled with a total energy recovery module for outdoor air preconditioning. These four DOAS serve variable air volume (VAV) air handling units, designed to handle the space sensible load requirements. The outdoor air dew point delivered by the DOAS is controlled based on the space humidity conditions in order to accommodate all of the outdoor and internal latent loads. At the direction of the owner, all systems at this site are packaged, vapor-compression heat pumps. This also includes the main VAV air handlers which are served by remote-mounted (split system), custom designed packaged heat pump condensing units. Extensive instrumentation was provided for all HVAC systems. Actual data is provided to show state points throughout the advanced HVAC system to summarize design performance at four separate outdoor conditions. The performance of the advanced system is compared to a conventional HVAC system to show the potential savings in energy consumption and peak demand. The advanced " integrated energy systems " approach detailed in this report provides an effective roadmap for constructing and operating comfortable, healthy, energy efficient schools (and other facilities) that follow current ASHRAE recommendations and meet all code requirements. This report also discusses the challenges and important design decisions that need to be made when selecting and installing a cogeneration system to serve active desiccant DOAS. The primary objective of this research project was to demonstrate the performance advantages of advanced " integrated energy systems " and " encourage further widespread adoption and implementation " of such systems. A further objective was to incorporate an advanced, integrated energy system into a conventional high school facility, where the level of design sophistication is typically limited and where budgetary concerns are high. This report summarizes a three-year project where a new high school facility was designed and constructed to combine a prepackaged cogeneration " prime mover " with prepackaged integrated active desiccant rooftop (IADR) systems to serve as dedicated outdoor air …