Cui J.,Kinki University |
Cui J.,Saibu Gas Co. |
Watanabe T.,Kyushu University
Journal of Environmental Engineering | Year: 2010
Currently,the air-conditioningload is calculated for transmissionthermalenergy fromthe wall surfacestoindoor air because theair-conditioning loadisdefinedforthe thermal energythat it should supplyindoor air with to keepafixed roomtemperature. Theair-conditioningload calculated in this waybecomesthe functionofthe room temperature set point and is unrelatedtothermalsensation ofthe resident.This paper suggested a new load calculation method which consideredthermalsensation of the residentbasedon a pointof viewof comfort air conditioning. By this new load calculation method,theload iscalculated for thermalenergy to removeby theroomto keep PMV ofthe indoor specificplace a setpoint. However,inintermittentair-conditioning system, theloadoccurs greatly to controlPMV in a set point in a shorttime.This paperis aimedat examining the effectivenessof the new loadcalculation method in intermittentair-conditioningsystem.
Cui J.,Kinki University |
Watanabe T.,Saibu Gas Co.
Journal of Environmental Engineering (Japan) | Year: 2012
In the past study, it was made clear that the load calculation method considering thermal sensation could calculate air conditioning load in consideration of spatial distribution of thermal sensation. However, even if air conditioning load is handled without overs and shorts because the load calculation method is not intended to cancel difference in thermal sensation in the room, thermal sensation at the examination point is kept by the required value, but thermal sensation at other points is not kept by the value that is similar to an examination point. Therefore there is concern that thermal sensation at the point except the examination point may be worsened by conditions adversely. This paper established an examination point and the reference point in the room and compared the difference of thermal sensation at the reference point with the examination point. The following results were obtained. 1) The difference of thermal sensation occurs between an examination point and a reference point, but the difference can be controlled in an acceptable range. 2) In convective air conditioning, the difference of thermal sensation does not almost occur. 3) In radiant air conditioning, the difference of thermal sensation changes by radiant panel position and required thermal sensation of examination point.
Chai Y.W.,Tokyo Institute of Technology |
Oniki T.,Tokyo Institute of Technology |
Kenjo T.,Tokyo Institute of Technology |
Kenjo T.,Saibu Gas Co. |
Kimura Y.,Tokyo Institute of Technology
Journal of Alloys and Compounds | Year: 2016
The microstructure and thermoelectric properties of an off-stoichiometric quaternary (Ti0.2,Zr0.8)Ni1.1Sn half-Heusler (HH) alloy was investigated in three heating cycles. A high density of coherent nanoprecipitates with an average diameter of ∼13 nm and an interprecipitate spacing of ∼6 nm was observed in the alloy. Formation of the extremely fine nanoprecipitates, most likely to be the 'full' Heusler (FH) phase, was not only strongly related to the degree of excess Ni concentration ratio in the alloy, but also appeared to be affected by the Ti-Zr substitutions. We noticed the behaviour of both electrical resistivity (ρ) and Seebeck coefficient (S) of the alloy was closely associated with the microstructure evolution of the FH-nanoprecipitates, which depended on their phase instability at elevated temperature and the cyclic heating process. The ρ and S reduced after the 1st heating cycle and stabilised thereafter in the subsequent heating cycles. Despite of the presence of the metallic FH-nanoprecipitates, the stabilised S maintained similar magnitudes to S of the ZrNiSn (without FH-nanoprecipitates) and did not show degradation of S as previously seen in the ZrNi1.1Sn containing relatively much larger FH-nanoprecipitates. The high density of FH-nanoprecipitates and the presence of Ti-Zr point defects were responsible for the significant reduction of thermal conductivity (κ) of the alloy, about 30% and 20% less than κ of the ZrNiSn and ZrNi1.1Sn alloys, respectively. Moreover, further reduction of κ was noticed due to formation of the diffuse HH/FH interfaced FH-nanoprecipitates from the cyclic heating process. Consequently, the alloy has shown a maximum dimensionless figure of merit (ZT) up to 0.81 at 870 K. © 2015 Elsevier B.V. All rights reserved.
Kobayashi K.,Osaka Gas Co. |
Sako T.,Osaka Gas Co. |
Yoshimi Sakaguchi,Osaka Gas Co. |
Morimoto S.,Tokyo Gas Co. |
And 4 more authors.
Journal of Natural Gas Science and Engineering | Year: 2011
The possibility of turbocharging into a natural gas homogeneous charge compression ignition (HCCI) engine is experimentally investigated. Experiments are performed using a naturally aspirated engine fitted with an external supercharger and a butterfly valve for back pressure control to simulate a turbocharger. The results indicate that the thermal efficiency can be improved by raising the engine compression ratio and lowering the boost pressure. At an engine compression ratio of 21 and turbocharging pressure of 0.19 MPa, the brake thermal efficiency reaches 43%, with NOx emissions of only 10 ppm or less. Finally, the performance of the engine fitted with a newly developed turbocharger is demonstrated. As a result, 43.3% brake thermal efficiency, 0.98 MPa brake mean effective pressure, and 13.8 ppm NOx emission have been realized. This value shows the possibility that a power generating efficiency of 40% at a power output of 50 kW could be achieved when applied to combined heat and power (CHP), even allowing for energy losses in the generator and the power inverter. For practical use, the ignition timing control, operation control, including how to start or load input and ensuring durability, remain to be investigated. To clarify these issues, we have initiated the endurance test for a newly developed 25 kW HCCI package, although the engine is not supercharged. © 2011 Elsevier B.V.
Tanaka H.,Osaka Gas Co. |
Suzuki A.,Tokyo Gas Co. |
Yamamoto K.,Saibu Gas Co. |
Yamamoto I.,Noritz Corporation |
And 2 more authors.
International Gas Research Conference Proceedings | Year: 2011
The ECOWILL, a micro-CHP system using an internal combustion gas engine, was unveiled in Japan in 2003 as the world's first mass-market product of its kind and has succeeded in establishing a new market in micro-CHP for household use. The ECOWILL consists of a 1kW output gas engine-powered generator unit developed by Honda and a hot water/space heating unit developed jointly by Osaka Gas, Tokyo Gas, Toho Gas, Saibu Gas and Noritz. The system uses gas as its primary energy source and is able to make efficient use of both heat and electrical power within the home. Combining energy savings with comfort, ease of use and convenience (usually mutually exclusive characteristics), the ECOWILL has been very well received by the market and has sold a total of 100,000 units nationwide as of 2010. This report describes the development of a new model of ECOWILL system with greater commercial appeal, aimed at the further popularization of micro-CHP, that addresses such issues as the need for installation in Japan's typically small urban dwellings and compatibility with Japanese energy-efficient housing, where technical progress is continually being made.