OAKTrust :: Browsing by Author "Yoshida, H."

Browsing by Author "Yoshida, H."

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Commissioning of a Coupled Earth Tube and Natural Ventilation System at the Acceptance Phase
(Energy Systems Laboratory (http://esl.tamu.edu), 2008-10) Pan, S.; Zheng, M.; Yoshida, H.
In this paper, the environment and energy performance of an actual coupled earth tube and natural ventilation system in a gymnasium was measured during the acceptance phase in two operation states: no ventilation and natural ventilation. From the measurement result, the authors found a design fault, which the airflow temperature from floor apertures on the north side was 3 degrees lower than from the floor apertures on the south side. By the use of the CFD (Computational Fluid Dynamics) coupled analysis with natural ventilation method, the natural ventilation air volume and the indoor temperature in three outdoor air conditions have been calculated to perform commissioning. Several findings were obtained and informed to the operator.
Commissioning of a Coupled Earth Tube and Natural Ventilation System at the Design Phase
(Texas A&M University (http://www.tamu.edu), 2007) Yoshida, H.; Pan, S.; Zheng, M.
Natural ventilation airflow rate is generally calculated using indoor and outdoor temperature difference without consideration of thermal interaction between the ventilated air and the room in simple analytical method based on pressure balance. However, room air temperature is influenced by natural ventilation airflow rate, and airflow rate is influenced by room air temperature, so it is necessary to perform a coupled analysis taking into account both thermal interaction and ventilation to obtain the correct result. Moreover, when there is marked temperature stratification, as found in large enclosures, or when ventilation airflow rate is small, significant computation error will occur if the set value of room air temperature differs greatly from the actual value. To solve the problems mentioned above, the authors developed a natural ventilation tool that takes into account indoor vertical temperature distribution and proposed a coupled simulation method using this tool in conjunction with CFD (Computational Fluid Dynamics) to simultaneously calculate indoor air flow/temperature distribution and natural ventilation airflow rate. In this paper, at the design phase of an actual coupled earth tube and natural ventilation system in a gymnasium, natural ventilation airflow rate for four outdoor air conditions have been calculated to perform commissioning and several findings were obtained.
Development of an Information Flow Mechanism for Commissioning
(Energy Systems Laboratory (http://esl.tamu.edu), 2008-10) Miyata, M.; Yoshida, H.; Yoshida, H.
The present paper proposes a new information flow mechanism for commissioning and develops tools to make the proposed information flow mechanism feasible. Although many technical tools have been developed in order to reduce the amount of labor necessary for commissioning, the information needed for the application of the tools to a real building is not rationally organized. It is necessary to manage and organize the necessary information rationally for the promotion of the usage of the tools. In order to resolve the issues of the present information flow, the present paper proposes a new information flow mechanism, which is constructed using a CAD data file, for example, IFC, SXF, or gbXML, a database, for example RDBMS of HDF5, and a process modeling method IDEF0. If the information about the building is organized rationally according to the proposed mechanism, the technical tools for commissioning can be applied easily and effectively, and the human error in the commissioning process can be reduced.
Energy Consumption Estimation for Room Air-conditioners Using Room Temperature Simulation with One-Minute Intervals
(Energy Systems Laboratory (http://esl.tamu.edu), 2006) Wang, F.; Yoshida, H.; Matsumoto, K.
For the purpose of developing optimized control algorithm for room air-conditioners to ensure their energy efficiency, a short time interval (i.e., one minute) simulation of building thermal performance is necessary because the sampling time interval for room air-conditioner control is one minute in general. This paper studies the short-time interval room air temperature simulation method using the response factor method. Using the simulated room air temperature, an air-conditioner's running time can be known so that its energy consumption can be estimated accurately. In order to verify the simulation accuracy, an actual room equipped with a gas-engine heat pump (GHP) air-conditioning system is studied by both simulation and measurement. The cooling amount produced by the GHP is calculated using measured refrigerant pressure and temperature at condenser and evaporator respectively. The Root Mean Square Error (RMSE) between measured cooling amount and simulated cooling load is 18.9 percent of the average measured value. The profile of simulated room air temperature in both air-conditioned daytime and nighttime without air-conditioning can match the measured room air temperature. With respect to the estimated energy consumption, the profile of simulated energy consumption can match the measured data. The simulation accuracy of room air temperature and energy consumption during the air-conditioner start-up period is not good and needs to be improved in future research. But in general, the verification shows that this energy consumption simulation method is acceptable for evaluating the energy performance of a room air-conditioner, and can also be a useful tool for commissioning room air-conditioners.
Estimation of Energy Baseline by Simulation for On-going Commissioning and Energy Saving Retrofit
(Energy Systems Laboratory (http://esl.tamu.edu), 2006) Miyata, M.; Yoshida, H.; Asada, M.; Iwata, T.; Tanabe, Y.; Yanagisawa, T.
This paper proposes a method of estimating the adjusted energy baseline using simulation models, which can calculate the energy baseline with various conditions, such as conditions of weather, occupancy and equipment operations. Especially, this paper reveals what detailed data the calibration of the model needs and the change of accuracy caused by different calibration data. Using the operational data of a middle-scale office building in Osaka Japan, the simulation accuracies of three models, which are calibrated using monthly energy consumptions of whole building (Level 1), monthly energy consumptions of subsystems (Level 2) and the detailed operational data of equipments (Level 3) respectively, are compared. The result shows that the differences of daily-integrated energy consumptions between measured value and simulated value using the model of Level 1 and 2 are not much different. The model of Level 3 is about 3% more accurate than the model of Level 1 and 2.
Experimental Study of a Cooling Coil and the Validation of its Simulation Model for the Purpose of Commissioning
(Energy Systems Laboratory (http://esl.tamu.edu), 2006) Yamaguchi, H.; Miyata, M.; Oda, H.; Shioya, M.; Watanabe, T.; Niwa, H.; Yoshida, H.
For HVAC system commissioning, it is important to evaluate the performance of the cooling coil in an air-handling unit. However, manual evaluation requires a great deal of time and effort. One solution is to predict the coil performance by simulation. However, it remains unclear whether the currently available simulation models can provide accurate results under various operational conditions. In the present study, a slit fin type coil was investigated by conducting two series of experiments, for the VAV system and the CAV system, respectively. In addition, the accuracy of seven simulation models was examined using the experimental data.
Fault Detection and Diagnosis Method for VAV Terminal Units
(Energy Systems Laboratory (http://esl.tamu.edu), 2004) Miyata, M.; Yoshida, H.; Asada, M.; Wang, F.; Hashiguchi, S.
This paper proposes two fault detection and diagnosis methods for VAV units without a sensor of supply air volume, and the results of applying these methods to a real building are presented. One method detects faults by applying a statistical method to four values calculated using the room air temperatures and the demand values of VAV damper opening of each unit during a steady state operation period. From the results of case studies, the method can reduce the number of units to be checked as faulty ones down to 12% of the total number and all the units that really have a fault are included in this group. The other method judges the faults by applying dynamic system analysis to the operational data when the VAV system starts up. From the result of the case studies, the method can reduce the number of units down to 30%, among which five units actually have a fault and only one faulty unit was not included in this group. Both methods can reduce time and cost for commissioning of VAV units significantly by the help of BEMS.
Model Based Commissioning Tool for Air-Conditioning Distribution Systems-APCBC
(Energy Systems Laboratory (http://esl.tamu.edu), 2014) Yoshida, H.; Noda, T.; Okayama Sciece University, Japan
Model-Based Commissioning for Filters in Room Air Conditioners
(Energy Systems Laboratory (http://esl.tamu.edu), 2004) Wang, F.; Yoshida, H.; Kitagawa, H.; Matsumoto, K.; Goto, K.
This paper proposes a model that can estimate filter resistance. Two sorts of value are used as inputs to estimate filter resistance. One is the power consumed by the fan in the indoor unit and the other is the thermal performance. For the room air-conditioners that the real time indoor unit fan power consumption is available, fan power consumptions are used as inputs to estimate filter resistance.For the room air-conditioners that are equipped with refrigerant pressure and temperature sensors, this model estimates filter resistance using refrigerant pressure and temperature, air temperature or enthalpy difference between supply and indoor air. The maximum and average difference between estimated and measured filter resistance are 12.72% and 5.89% when using the fan power consumption as inputs. When using the air-conditioner thermal performance data, the maximum and average estimation errors are13.12% and 5.96%. Based on this model, the method for commissioning filters in air-conditioner is discussed.
Optimal Well-Group Distribution of a Groundwater Source Heat Pump System
(Energy Systems Laboratory (http://esl.tamu.edu), 2006) Liu, Z.; Lu, L.; Yoshida, H.
It is critical to determine how the well group arranges for application of the GWSHP system. Based on the fact that water movement is the most important factor influencing heat transfer in an aquifer, this paper presents a two-step analysis method and analyzes the inter-well thermal transfixion method as follows. First, we forecast the least influence radius through calculating the thermal diffusion function of aquifer. Then, we perform an analysis on the inter-well thermal transfixion, using the streamline analysis method and doing a quantitative analysis of the effects that inter-well distance and flux have on it. We discuss the well group arrangement and puts forward optimal scheme by means of the thermal diffusion and streamline simulation.
Preliminary Retro-Commissioning Study on Optimal Operation for the Heat Source System of a District Heating Cooling Plant
(Energy System Laboratory (http://esl.tamu.edu), 2008-10) Shingu, H.; Yoshida, H.; Wang, F.; Ono, E.
In order to improve the energy performance of a district heating and cooling (DHC) plant, the expected performance of the plant is studied using simulations based on mathematical models. A complete heat source system model, equipped with an embedded module that automatically determines the on/off states of heat source equipment using cooling/heating loads, has been developed and validated using actual performance measurements. The mean error between the simulated and measured total energy consumption was 4.2%. Using the developed model, three proposals for improving the plant operation are simulated in order to determine how much energy can be saved. The simulation result shows that the three proposals, automating primary water flow rate, fully open bypass valve of heat exchanger during no-ice-thermal-discharge period, and increase chilled water supply temperature to 8°C, could reduce plant total energy consumption by 2.1%, 0.7% and 3.3% respectively.
Pressure Differential Analysis of a Laboratory Animal Room
(Energy Systems Laboratory (http://esl.tamu.edu), 2006) Jiang, X.; Liu, Z.; Yoshida, H.; Tang, B.
This paper simulated and analyzed the pressure differential of a laboratory animal room by CFD software. Under a certain wind speed, the windward side pressure distribution of laboratory animal room was studied, and the windward side pressure differential distribution function was drawn. The corresponding distribution law and maximum wind pressure point were found. At the same time, the indoor pressure among the laboratory rooms was studied and simulated when the door opened, to learn what pressure differential can prevent air flow from a low pressure region to a high pressure region. We tested whether the differential pressure is reasonable to regulate the code between the indoors and outdoors, and among laboratory animal rooms, so as to provide a certain reference for code, construction and design, and to decrease positive pressure air change and save energy based on inside air environment requirements.
Requirements for Commissioning HVAC Systems Using BEMS and Commissioning the BEMS Itself Based on Questionnaire Surveys
(Energy Systems Laboratory (http://esl.tamu.edu), 2004) Yoshida, H.; Vaezi-Nejad, H.; Choiniere, D.; Wang, F.
In this paper the present status and requirements for commissioning of HVAC Systems using Building Energy Management Systems (BEMS) and commissioning the BEMS itself are investigated and summarized. The information presented is based on the results of the questionnaire and interview survey of experts which was carried out in four countries; Japan, the USA, France and Canada. This paper intends to clarify the requirements and future scope of the above issues by analyzing similarities and differences between the countries.
Retro-Commissioning and Improvement for District Heating and Cooling System Using Simulation
(Energy Systems Laboratory (http://esl.tamu.edu), 2006) Shingu, H.; Nakajima, R.; Yoshida, H.; Wang, F.
In order to improve the energy performance of a district heating and cooling (DHC) system, retro-commissioning was analyzed using visualization method and simulation based on mathematical models, and improved operation schemes were proposed according to simulation analysis results. The first part of this paper describes the system performance through visualizing the current operation modes. The second part introduces the retro-commissioning analysis for the system using mathematical models of each component. The third part studies the energy and cost performance of several improved operation proposals using simulation. The results are as follows.1) The carpet plots of current operation modes can be generated automatically and they are useful to check whether the operation is proper or not. 2) The total system simulation model was constructed. The simulation error of the total energy consumption was 1.5% and the percentage of root mean square error (%RMSE) was 16.3%, which show that the simulation is accurate enough to study the performance of proposed operation.3) System simulations for proposed operation schemes were performed. The simulation results show that the system operation with the optimal temperature set point of cooling water at 22oC can improve the total energy coefficient of the heat pump and cooling tower by 2.2 %. Another proposal is that if the return water temperature from users can be kept at the designed value, which is 13±1? compared with the current average value of 10.5?, the total energy consumption can be reduced by 9.5%, and energy cost can be reduced by 11.6%.
The Well-Group Distribution of Groundwater Source Heat Pump System Optimized Research
(Energy Systems Laboratory (http://esl.tamu.edu), 2006) Liu, Z.; Lu, L.; Yoshida, H.
It is the key question that how does the well group arrange for application of GWSHP system. Based on the fact that the water movement is the important factor of heat transfer on aquifer, this paper presents two steps analysis method and analyze the inter-well thermal transfixion, method as follows: (1) Forecast the least influence radius through calculating the thermal diffusion function of aquifer; (2) The analysis on the inter-well thermal transfixion makes use of the streamline analysis method and makes quantitative analysis of the effect that inter-well distance and flux make on it. It labors the well group arrangement and puts forward optimal scheme by means of the thermal diffusion and streamline simulation.

Browsing by Author "Yoshida, H."

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