DOE EERE Research Reports

Distributed Energy Resources and Combined Cooling, Heating, and Power

CHP Integration

Integration of Distributed Energy Resources and Thermally-Activated Technologies
D. Tom Rizy
Abdi Zaltash
Solomon Labinov
Andrei Petrov
Phil Fairchild
Cooling, Heating, and Power Group
Engineering Science and Technology Division
Oak Ridge National Laboratory
Oak Ridge, Tennessee

Abstract: A new CHP Integration Test Facility has been commissioned at the Oak Ridge National Laboratory (ORNL) for the testing of distributed energy resources (DER) combined with thermally-activated technologies for combined cooling, heating, and power (CHP). Presently, it has been set up to test a 30-kW microturbine with both direct and indirect-fired desiccant dehumidification systems and a 10-ton indirect-fired single-effect absorption chiller. The first phase of testing has been completed which examined both the startup and shutdown capabilities and limitations of the microturbine and its load following performance. The performance testing determined the variability of the microturbine’s operating performance variables, such as power output, voltage, current, and heat output as well as its power output ramping characteristics for load following. Nominally, the microturbine’s maximum power output and efficiency without waste heat recovery are 28 kW and 23%, respectively. The efficiency of the microturbine drops as the power output and turbine speed are reduced. The efficiency of the microturbine at one-third rated power output or 10 kW is 18%. Once up and running the microturbine can vary its power output such as from 10 to 20 kW in 20 s although it requires 200 s or close to 3.5 minutes for cold startup. The goal of the DER/CHP test facility at ORNL is to increase the efficiency of the DER/CHP electric and thermal power plant by optimally integrating both the packaging and operation of the various components. Nominally the exhaust heat from the microturbine at full output is ~500°F (~260°C). The exhaust heat can be used directly by mixing it with outside air to get the correct inlet temperature (~220°F or 105°C) for the direct-fired dehumidifier or fed to an air-to-water heat exchanger to obtain hot water (~180°F or 82°C) for an indirect-fired dehumidifier or absorption chiller. At the ORNL DER/CHP test facility, the hot air ducting and hot water plumbing have been completed and various waste heat recovery tests are underway. Prior to these tests, a series of exhaust backpressure tests were conducted to determine the performance impacts on the microturbine for expected backpressure of the thermally-activated technologies. It has been found that exhaust backpressures of up to ~1.7x10-2 atm or 7 inches of water column (in wc) can be applied without producing any significant reduction in the energy efficiency or power output of the microturbine. In fact, the speed of the turbine increases as the backpressure is applied which consequently does not significantly impact the power output or efficiency of the microturbine. In this paper, the microturbine’s performance results for startup/shutdown, load variation, and backpressure testing are provided and discussed. Also, preliminary results of testing the microturbine with indirect-fired thermally-activated technologies, which were conducted this winter are presented and discussed.

Keywords: microturbine, absorption chiller, desiccant dehumidifier, efficiency, thermally activated technology, distributed energy resource, der

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