scholarly journals THE OPTIMIZATION OF CONTROL PARAMETERS FOR A VAV HVAC SYSTEM : Influence of mutual interference between VAV damper and fan inverter operations on room temperature control performance

2007 ◽  
Vol 72 (618) ◽  
pp. 77-84 ◽  
Author(s):  
Katsuki MAEHARA ◽  
Noriyasu SAGARA
Author(s):  
Jia-liang Song ◽  
Wen-long Cheng ◽  
Zhi-ming Xu ◽  
Shuai Yuan ◽  
Ming-hou Liu

2021 ◽  
Vol 92 (7) ◽  
pp. 075108
Author(s):  
Yilun Xu ◽  
Gang Huang ◽  
David I. Santiago ◽  
Irfan Siddiqi

Author(s):  
Jinwei Chen ◽  
Yuanfu Li ◽  
Huisheng Zhang ◽  
Zhenhua Lu

Abstract The SOFC performance and lifetime highly depend on the operation condition, especially the SOFC operation temperature. The temperature fluctuation causes thermal stress in electrodes and electrolyte ceramics. On the other hand, it also needs to maintain a sufficiently high temperature to enable the efficient transport of oxygen ions across the electrolyte. Therefore, it is necessary to design an effective SOFC temperature management system to guarantee safe and efficient operation. In this paper, a two-side temperature control method is proposed to avoid the temperature difference between anode and cathode. Therefore, the SOFC thermal management system includes two control loops. The anode inlet temperature and cathode inlet temperature are controlled by blowers adjusting the recirculated flow rate. In addition, the control performance of the proposed SOFC thermal management system is compared with one-side temperature control systems. The results show that both anode control loop and cathode control loop are essential to get a better control performance. The SOFC would operate with less efficiency with only anode temperature control. On the other hand, the safety problem would occur with only cathode temperature control. The temperature gradient would be more than the upper limit at a part load condition. Therefore, the SOFC thermal management strategy with anode and cathode temperature control loops is feasible for the SOFC-GT system.


2019 ◽  
Vol 9 (11) ◽  
pp. 2391 ◽  
Author(s):  
Chang-Ming Lin ◽  
Hsin-Yu Liu ◽  
Ko-Ying Tseng ◽  
Sheng-Fuu Lin

The objective of this study was to develop a heating, ventilation, and air conditioning (HVAC) system optimization control strategy involving fan coil unit (FCU) temperature control for energy conservation in chilled water systems to enhance the operating efficiency of HVAC systems. The proposed control strategy involves three techniques, which are described as follows. The first technique is an algorithm for dynamic FCU temperature setting, which enables the FCU temperature to be set in accordance with changes in the outdoor temperature to satisfy the indoor thermal comfort for occupants. The second technique is an approach for determining the indoor cold air demand, which collects the set FCU temperature and converts it to the refrigeration ton required for the chilled water system; this serves as the control target for ensuring optimal HVAC operation. The third technique is a genetic algorithm for calculating the minimum energy consumption for an HVAC system. The genetic algorithm determines the pump operating frequency associated with minimum energy consumption per refrigeration ton to control energy conservation. To demonstrate the effectiveness of the proposed HVAC system optimization control strategy combining FCU temperature control, this study conducted a field experiment. The results revealed that the proposed strategy enabled an HVAC system to achieve 39.71% energy conservation compared with an HVAC system operating at full load.


2008 ◽  
Vol 41 (1) ◽  
pp. 214-216 ◽  
Author(s):  
Christine Lavigueur ◽  
E. Johan Foster ◽  
Vance E. Williams

An inexpensive capillary furnace has been developed for variable-temperature X-ray diffraction in transmission geometry of air-stable liquid crystals and other materials. It offers temperature control with fluctuations of less than ±1 K in the range of interest for these samples, from room temperature to near 573 K. Phases can be accessed through heating or cooling with no significant overshooting of the target temperature. The furnace is designed to fit on a classical goniometer, and can be controlled by any standard temperature controller. The simple design of this furnace means that it is both inexpensive to build and easy to operate.


Sign in / Sign up

Export Citation Format

Share Document