1、OR-05-9-3 Dynamic Performance of a 30=kW Microturbine-Based CHP System Andrei Y. Petrov, PhD Member ASHRAE Abdolreza Zaltash, PhD Member ASHRAE D. Tom Rizy Solomon D. Labinov, PhD Randall L. Linkous ABSTRACT The goal of the Cooling, Heating, and Power (CHP) Program established in 2000 by the US Depa
2、rtment of Energy (DOE) is to provide research, development, and testing (both laboratory and field) and to accelerate implementation of distributed electric generation (DG) with thermally activated technologies (TAT). The objective is to provide DG with waste heat recovery, i.e., combination ofDGand
3、 waste heat recovery utilization to drive various TATunits (heat recovery, desiccant, absorption chiller units, etc.) and increase overall fuel efi- ciency of the technology. Dynamic tests of the CHP system, which were performed at the CHP Integration Laboratory of the Oak Ridge National Laboratory
4、(ORNL), are presented. The CHP system at the lab includes: a 30-kW microturbine generator, an air-to-water heat recovery unit, an indirect-red single-effect 1 O-ton (35-kW) absorption chiller, and indirect- and direct-red desiccant dehumidification units. The dynamic system response of the CHP syste
5、m was tested during both cold-start-up and power-dispatch (changing electric/ thermal demand) modes. The test results provide valuable information for both understanding CHPperformance as well as for use to develop better control tools for CHP equipment. INTRODUCTION DOES Cooling, Heating, and Power
6、 (CHP) Program was established in 2000. Its primary purpose is to provide research, development, and testing in order to accelerate implementa- tion of distributed electric generation (DG) with thermally activated technologies (TAT). The objective of the CHP Inte- gration Laboratory is to provide a
7、test bed for testing combined electric power generation and waste heat recovery utilization to drive various TAT units. The benefits of CHP include having both electric and thermal energy available from the same system and increasing overall fuel efficiency (NEP 2001). CHP system performance is an i
8、mportant aspect since some of these systems are intended to be used during backup/ emergency situations, and the time needed to reach a certain electrical/thermal demand from a cold start or during a load change becomes a crucial limiting factor. Also, the results of dynamic testing provide valuable
9、 data needed to create a dynamic model of the CHP system and provide input for developing better control hardware and software for the tech- nology. The dynamic performance of the 30-kW microturbine generator, which is a component ofthe CHP system presented in this paper, was previously outlined by
10、Langley et al. (2002), Rizy et al. (2002), and SCE (2004). Dynamic performance aspects of the CHP system with direct-fired desiccant dehu- midification unit are given by Petrov et al. (2004), so it is not considered in this paper. SYSTEM CONFIGURATION AND TEST EQUIPMENT The CHP system, which was tes
11、ted at the CHP Integration Laboratory, consists of a 30-kW microturbine generator (MTG), an air-to-water heat recovery unit (HRU), an indirect- fired (hot water-fired) IO-ton (35 kW) single-effect absorption chiller (AC) with air-handling unit (AHU), an indirect-fired desiccant dehumidification unit
12、 (IFDD), and a direct-fired desiccant dehumidification unit (DFDD) (Zaltash et al. 2003). The CHP system diagram is shown in Figure 1. The IFDD was used in these tests as a variable thermal load on the HRUs output (water side). There is an insulated air-duct ventilation system from the MTGs exhaust
13、to the HRU and to the DFDD. The flow from either of these TAT units is controlled via dampers. Also, there is a water loop from the HRU to the IFDD andor AC. - - A.Y. Petrov is a research associate, A. Zaltash is a research staff member, S.D. Labinov is a senior R for example, the heat recovery proc
14、ess does not begin simultaneously with the MTG start-up. The HRU operates in a “bypass” mode, which isolates the heat exchanger from the MTG exhaust gas by the HRUs diverter valve until the temperature of MTG exhaust gas at the inlet to HRU reaches a temperature setpoint value (195f5”F or 90.5f2.5”C
15、). The HRU uses the bypass mode to ASHRAE Transactions: Symposia 803 Table 1. Instrumentation and Measurement Precisions at the CHP Integration Laboratory Measurement Temperature Dew-point temperature Dew-point temperature Air flow Sensor Range Precision Resistive temperature detector -328 to 1,562F
16、 *0.2F (kO.lC) (-200 to 85OOC) Chilled mirror -40 to 140F zt0.2F (*O.lC) (-40 to 6OOC) Humidityhemperature transmitter -40 to 140F *0.4OF (*0.2OC) (-40 to 2 12OC) Fan evaluator* 500 to 5,000 scfm *2% (14.2 to 141.6 m3/min) I Water flow Gas flow - MTG Gas pressure - DFDD Gas pressure - MTG Power - MT
17、G Flow meter Pulse count test meter O to 415 cfh *0.2% 1 O pulseskf Pressure transducer (O to 11.8 m3h) O to I5 in wc (O to 3.73 kPa) O to 200 in wc (O to 49.73 kPa) Watt transducer O to 40 kW *OS% of full scale (O to 136,577 Btuh) *OS% of full scale Pressure transducer +OS% of full scale O to 100 g
18、pm (O to 0.38 m3/min) CHP System Startup with MTG Set for 20 kW *lYo CHP System Startup with MTG Set for 30 kW I Gas flow - DFDD 95.0 (35.0) 35.0 (1.7) Steady-State Percent Transient Value Deviation Time, min 20.0 O) could reach 20 minutes. Unfortunately, the operational condi- tions of the HRU comp
19、onent of the CHP system can?t always provide successful start of the AC operation with the first attempt. The first attempt doesn?t always produce sufficient thermal input to the AC unit (setpoint hot water temperature required to operate the AC could not be maintained). It was found that it usually
20、 requires two to three attempts before the AC starts to produce useful cooling capacity. The fluctuations caused by these attempts are not shown in Figure 8 in order to simpliQ it. In addition, the time constants do not include these attempts. The time between HRU and AC start-ups is usually 10 to 1
21、5 minutes. The use of hotter MTG exhaust or a more effective HRU could significantly reduce the AC start-up time or ensure successful start-up with the first attempt. Tests with the current CHP configuration determined that the transition 808 OS 1 138.6 (59.2) I 8.0 I I 9.0 I OS I 144.3 (62.4) time
22、to reach steady state for the AC (cooling capacity and chilled water temperature) is -70 minutes from the MTG start- up or 50 minutes from the AC successful startup. Figure 9 shows the dynamic trends of the HHV-based MTG and total CHP efficiencies, as well as the COP ofthe AC, which are calculated a
23、ccording to Zaltash et al. (2003). Results show that the transient times are tied to the MTG start-up and are similar to those of the AC cooling capacity and the chilled water outlet temperature, ie., dynamics of total CHP effi- ciency is governed by the AC performance. The time constants of the maj
24、or performance parameters for this CHP system are shown in Table 5. Note that the values for the AC are much lower than for the HRU. Figure 10 shows the effect of ambient temperature on the dynamic behavior of the MTG from cold start to maximum available power output at full (30 kW) power setting. R
25、esults show an increase in transient time with ambient temperatures. This seems to be the result of the controller and control scheme used by the manufacturer of this MTG. CONCLUSIONS A series of CHP system tests were performed with differ- ent combinations of commercially available equipment to mea
26、sure the transition times and time constants for reaching steady-state operation during cold start-up and after load ramping. The test results show that the thermally activated components of the CHP systems have much more thermal inertia than the MTG (electric generator) component. The dynamic perfo
27、rmance of the MTG component of the CHP system for the most part varies nearly proportionally to the net power output of the MTG. The largest time constant of the CHP system is attributed to the HRU exhaust gas temperature. The activation modes of the HRU and AC directly impact the transition times o
28、f the CHP system. They both operate with bypasslrecovery modes that activate only when the input temperature reaches a setpoint value. In the case of the HRU, the setpoint of the inlet temperature of the HRU or the MTG ASH RAE Transactions: Symposia exhaust gas temperature must be -195F (90.5“C) bef
29、ore the HRU switches from the bypass to the recovery mode. In the case of the AC, the setpoint of the inlet temperature of the AC or the HRU water outlet temperature must reach -160F (71OC). These types of test results provide important insight to CHP performance characteristics and valuable input f
30、or model development that can be used in simulation of dynamic perfor- mance and implementation of better control tools for CHP systems. Future testing of a CHP system with a larger MTG is planned to evaluate how the increased size and make may affect dynamic time constants. It is important to note
31、that the time constants measured during these tests are also a function of the existing controls and control schemes used by the vari- ous CHP system components (i.e., the MTG). It should be noted that this study only addresses the dynamic behavior of two specific commercially available CHP combinat
32、ions. Furthermore, the electric generator is of only one type (MTG) and further CHP system testingusing different generators (i.e., reciprocating engines) is planned to gather information on their dynamic performance characteristics. NOMENCLATURE AC AHU - CHP - COP - DFDD - HHV - IFDD - HRU - MTG -
33、(?chilled - - - QHRU - Tamb THRU hot water out - TAC chilled water out - - - - WMTG absorption chiller air-handling unit combined cooling, heating, and power coefficient of performance direct-fired dehumidification unit higher-heating value of natural gas indirect-fired dehumidification unit heat re
34、covery unit microturbine generator cooling capacity of absorption chiller heat recovered by the HRU ambient temperature hot water outlet temperature of the HRU chilled water outlet temperature of the AC electric power output of the MTG ACKNOWLEDGMENTS The authors would like to thank the Office of En
35、ergy ER- ciency and Renewable Energy, U.S. Department of Energy OE), for supporting this work. This research was also supported in part by an appointment to the Oak Ridge National Laboratory (ORNL) Postdoctoral Research Associates Program administered jointly by the Oak Ridge Institute for Science a
36、nd Education and ORNL. This work was conducted by ORNL under DOE contract DE-AC05-000R22725 with UT-Battelle, LLC. REFERENCES Langley, R., T. Key and D.T. Rizy. 2002. Steady-state and dynamic performance characterization testing of a microturbine. Proceedings of the Power System Confer- ence, Impact
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39、ash, E.A. Vineyard, S.D. Labinov, D.T. Rizy, and R.L. Linkous. 2004. Baseline, exhaust-fired, and combined operation of desiccant dehumidification unit. Paper submitted to the 2004 ASME International Mechanical Engineering Congress and Exposition, November 13-19, 2004, Anaheim, CA, paper Rizy, D.T.,
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41、ll microtur- bine generators during load changes. Public interest energy research final report, publication 500-04-033, prepared for California Energy Commission. Rancho Cucamonga, CA: Southern California Edison. Zaltash, A., A.Y. Petrov., D.T. Rizy, S.D. Labinov, E.A. Vineyard, and R.L. Linkous. 2003. Laboratory research on integrated energy systems (IES). Proceedings of the 21st International Congress of Refrigeration, August 17-22, 2003, Washington, DC, paper ICR0203. IMECE2004-60264. SC, pp. 1-6. ASHRAE Transactions: Symposia 809
