Wide area network discrete feedback control on FastADR of a cluster of building air‐conditioning facilities

Building air‐conditioning facilities are promising resources of the fast automated demand response (FastADR) aggregation. However, designing a closed‐loop control includes problems of strong nonlinear dynamic properties of the facility and large sampling period due to building facility communications. This paper proposes an original aggregated transfer function that approximates hundreds of air‐conditioners with large wide area network communication delays. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Heat transfer and pressure loss characteristics of a heat exchanger for recovering latent heat (effects of straight fin length and fin pitch on the heat transfer and pressure loss characteristics)

In recent years, the requirement for the reduction of energy consumption has been increasing to solve the problems of global warming and the shortage of petroleum resources. A latent heat recovery type heat exchanger is one of the effective methods for improving thermal efficiency by recovering latent heat. This paper describes the heat transfer and pressure loss characteristics of a latent heat recovery type heat exchanger having straight fins (fin length: 65 mm or 100 mm, fin pitch: 2.5 mm or 4 mm). These were clarified by measuring the exchange heat quantity, the pressure loss of the heat exchanger, and the heat transfer coefficient between the outer fin surface and gas. The effects of fin length and fin pitch on heat transfer and pressure loss characteristics were clarified. Furthermore, equations for predicting the heat transfer coefficient and pressure loss which are necessary for heat exchanger design were proposed. ©2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(4): 230– 247, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20153 Copyright © 2004 Wiley Periodicals, Inc.     

Theoretical performance analysis on transmission reserve table buffer with triage ranking for resource‐limited control networks

Performance of the ‘transmission reserve table’ (TRT) buffer, which the authors recently proposed, is theoretically investigated. The buffer's triage ranking queuing was designed for resource‐limited control networks that are possibly exposed to a rush of control commands. Our previous study analyzed the performance of the TRT buffer by means of computer simulation. In this paper, we derive a stochastic analytical model for the TRT buffer and verify the model in comparison with computer simulations. Theoretical calculation demonstrates that the triage ranking of the TRT plays a crucial role in keeping the real‐timeness of the control network even in a rush of commands by our triage ranking mechanism. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Scalability analysis on the smart grid fast automated demand response aggregation Web services for widely distributed building facilities

In this paper, we modeled an aggregation communication server of the Fast Automated Demand Response (FastADR) system using an M/M/1 queuing system. Assuming that a very large number of FastADR participating BEMS gateways are widely distributed, scalability of aggregation communication performance was estimated by the M/M/1 transient analysis. Validity of our analysis model was confirmed by realistic wide‐area communication emulation system in the laboratory. Our scalability analysis has shown that at least parallel 25 aggregation systems will be necessary to realize expected communication time of approximately 30 s for an example of FastADR aggregation of 100 MW reduced demand.     

Aggregated transfer function for smart grid FastADR feedback control of wide area distributed building facilities

Feedback control of fast automated demand response (FastADR) is gaining much attention for load frequency control (LFC) of the future smart grids. We propose a single aggregated transfer function for feedback control of power consumption of a cluster of wide‐area‐distributed building air‐conditioner facilities. An example of aggregated transfer function is derived from the measured step responses of the loads, and the effectiveness of the approximation for control properties is confirmed by simulations. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Reaction Kinetics of Coke and some Carbonaceous Materials with CO2 and Coke Strength after Reaction

The reaction rate per unit mass of wood char was an order of magnitude larger than that of coke and graphite and that of glassy carbon was an order of magnitude smaller than the latter. However, the reaction rate per unit surface area of wood char was smaller than that of graphite. The reaction of coke proceeded homogeneously at temperatures lower than 1373 K, while the reaction was restricted to the surface layer at higher temperatures. The tensile strength of coke after reaction decreased with the reaction degree at 1273 K, but was not changed or even increased at 1573 K. This is due to the fact that at 1573 K the core of the sample was not attacked by CO₂ but strengthened by further crystallization.     

The heat transfer and pressure loss characteristics of a heat exchanger for recovering latent heat (the heat transfer and pressure loss characteristics of the heat exchanger with wing fin)

In recent years the requirement for reduction of energy consumption has been increasing to solve the problems of global warming and the shortage of petroleum resources. A latent heat recovery type heat exchanger is one of the effective methods of improving thermal efficiency by recovering latent heat. This paper described the heat transfer and pressure loss characteristics of a latent heat recovery type heat exchanger having a wing fin (fin pitch: 4 mm, fin length: 65 mm). These were clarified by measuring the exchange heat quantity, the pressure loss of heat exchanger, and the heat transfer coefficient between outer fin surface and gas. The effects of condensate behavior in the fins on heat transfer and pressure loss characteristics were clarified. Furthermore, the equations for predicting the heat transfer coefficient and pressure loss which are necessary in the design of the heat exchanger were proposed. ©2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(4): 215–229, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20154     

Analysis on burst packet buffering of communication gateway between fast IP network and slow facility fieldbus

In the Internet of Things (IoT) age, fieldbuses for distributed embedded systems are often integrated with IP networks with gateways. Because of the vast difference in bit rates between both networks, buffering characteristics of these gateways are becoming important. In this paper, we modeled a fieldbus gateway using an M/M/1 queuing system for the transient packet buffering. Assuming burst packet arrivals at the gateway, time trends of the expected value and the standard deviation of the number of buffered packets were calculated analytically. Validity of our analysis was confirmed using computer simulation for CSMA/CD communications. Time trend curves for the expected value and the standard deviation matched within 5% and 20 %, respectively. Our transient analysis method provides a practical estimation method for the transient performance of the fieldbus gateways. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.