Aleph Networks Co. 2 Advanced Control System Optimizing control for the Energy of the Heat Source System 1

Aleph Networks Co. 2 Case1: Optimizing control for the Heat Source System with water cooled chillers Ritsumeikan Univercity 2

Aleph Networks Co. What is Optimized Operation Control?  An optimal technique where multiple fixed set points for controlling air-conditioning system are to be set to appropriate values depending on the daily situations. →Combinations of several set points are determined to minimize energy consumption.  Our company has developed several tools to optimize heat source operation on a real-time basis.  The tools can read meteorological data and operation data of air- conditioning system, and computes the optimal set points in real time to change them for optimal control.  IT technology is applied to this control method to cope with more sophisticatedly. 3

Aleph Networks Co. Operating BEAMS (Aleph Network product for BEMS), control device and PC for optimization calculation on the same network. Obtaining optimal solution for the entire control system, not for individual control. Mechanism of Optimized Control for Heat Source System Operation Development of Partial-Load Control Simulation developer Remote access PC for optimal calculation HVAC system simulation Calculation of optimal values Meteorological data Operation data Optimal set points Control device Meteorological data Operation data storage (database) Function to change set points Development/ updating maintenance Operation data Set points 4

Aleph Networks Co. 空調システムの概要 Outline of Target Heat Source System Development of Partial-Load Control Chilled water flow rate 5800L/min Cooling water flow rate(INV) 6000 ～ 9000L/min Cooling water flow rate is controlled by temp. difference of cooling water at CT inlet/outlet. The no. of CT fan units is controlled by cooling water temp. at CT outlet. West wing buildingEast wing building Heat source capacity 685USRT R-3 (gas absorption type) R-2 (gas absorption type) R-1 (gas absorption type) Pressure transmitterDifferential pressure type flowmeterInsertion type tem. Sensor (planned to install) Insertion type tem. SensorElectromagnetic meterGas meter (with pulse transmitter)Inverter Power sensor 5

Aleph Networks Co. Purpose of Study Optimization Assessment Absorption refrigerating machine ・ Cooling water temp. setting→low ⇒ Gas consumption on absorption type chiller/heater decreases Power for cooling tower fan increases ・ Heat source cooling water temp. difference setting→large ⇒ Power on cooling water pump decreases Most effective combination of these set points needs to be found. Refrigeration capacity [%] Cooling water inlet temperature Gas consumption (m3 (standard condition)/GJ) 6

Aleph Networks Co. Optimization Problem (1)  Optimization of heat source system operation Obtain the temp. SPs of cooling water at CT outlet and the difference between inlet and outlet of CT that make energy consumption sum of equipments minimal. 【 Target equipment 】 heat source equipment, primary cooling water pump, cooling tower fan and cooling water pump  Optimization based on simulation （ Implementation of optimization: every hour) Input:outdoor temp. and humidity, secondary side load, cooling water temp. SP at CT outlet and temp. difference SP between CT inlet and outlet. Outdoor temp. and humidity and secondary side load should be actual operation data of 60 min. before optimization. (Measurement interval: 1 min. Computation interval: 1 min.) Output: energy consumptions of all equipments 7

Aleph Networks Co. 1) Objective function (sum of energy consumption) 2) Variable of optimization Cooling water temp. at CT outlet (24 ～ 32 ℃ ) Temp. difference of cooling water between CT inlet and outlet (3 ～ 7 ℃ ) 3) Boundary condition Load in the secondary side, outdoor temp. and humidity 4) Constraint Cooling water flow rate max./min. values Air volume of cooling tower fan max./min. values Optimization Problem (2) Development of Partial-Load Control 【 Computation flow for optimization (all possible regression) 】 CT outlet cooling water temp. that gives SP combination (T CT =24,25…31,32deg C) CT cooling water temp. difference at inlet/outlet (D CT =3,4…6,7 deg c) Computation of primary energy equivalent En of primary HVAC system Input values (secondary side load, outdoor temp. and humidity) SPs were computed in all combination Operate with SP T, SP D 8

Aleph Networks Co. Development of Simulation Model Rated capacity per unit No. of units in operation Load in the secondary side Control model by no. of units Primary pump model Cooling water pump model Gas absorption chiller/heater model Cooling water flow rate control model Cooling tower model Control model by no. of CT fan operating units Cooling water flow rate Primary pump power consumption Cooling water temp. difference SP at inlet/outlet of cooling tower Cooling water temp. SP at outlet of cooling tower Meteorological conditions (outdoor temp. humidity) Heat source gas consumption Heat source power consumption Cooling water temp. at outlet of heat source Cooling water pump power consumption CT fan power consumption Cooling water temp. at outlet of cooling tower No. of units of CT fan in operation 9

Aleph Networks Co. i =0i =1i =3 aiai bibi cici E-0.5 Input ： Load factor r q, Cooling water temp. at heat source inlet θ wrc,i, Cooling water flow rate v wrc Output:Gas consumption r g, Cooling water temp. at heat source outlet θ wrc,o Example of Modeling Equipment (Heat Source : Gas-Fired Absorption Chiller/Heater) Development of Partial-Load Control Performance curve provided by manufacturer Load factor [%] Gas consumption [%] (Estimated values) (Performance curve) (Estimated values) (Performance curve) (Estimated values) 10

Aleph Networks Co. ガス消費率の比較 Average error:Gas consumption 0.12m 3 /h(0.17%) ， Cooling water temp ℃ (0.09%) Squared error:Gas consumption 3.78m 3 /h(5.33%) ， Cooling water temp ℃ (1.21%) Correction coefficient:1.403 熱源出口冷却水温度の比較 Verification Example of Modeling Equipment Correction Based on Actual Metering （ Heat Source : Gas-Fired Absorption Chiller/Heater) Development of Partial-Load Control Comparison of gas consumption rate Gas consumption rate [%] Comparison of cooling water temp. at outlet of heat source Cooing water temperature Comparison of gas consumption rate (metered value) Comparison of gas consumption rate (estimation before correction) Comparison of gas consumption rate (estimation after correction) Outlet cooling water temp.(metered value) Outlet cooling water temp.(estimation) Outlet cooling water temp.(estimation before correction) 11

Aleph Networks Co. Optimized Control for Heat Source System Operation Online Verification (1) Development of Partial-Load Control 4 ％ reduced 10 ％ reduced ● Comparison between August and September in 2007 before optimization and in 2008 after optimization 10.6 ％ improved 11 ％ improved Fig. 1 Comparison of integrating primary energy consumption (Aug) Fig. 2 Comparison of integrating primary energy consumption (Sep) Monthly integrating primary energy consumption (GJ) Aug. 2007Aug. 2008Sep. 2007Sep Equipment COP [-] System COP [-] Fig.4 Comparison of system COP Fig.3 Comparison of equip.COP of gas absorption chiller/heater Secondary side load factor [%] Monthly average equip. COP Monthly average system COP Aug Aug Aug. Sep Sep Sep Aug. Sep Equip.COP 2007 Equip.COP 2008 System COP 2007 System COP 2008 Power consumption of cooling tower fan Power consumption of cooling water pump Gas consumption of chiller/heater Power consumption of cooling tower fan Power consumption of cooling water pump Gas consumption of chiller/heater 12

Aleph Networks Co. Optimized Control for Heat Source System Operation Online Verification (2) Development of Partial-Load Control ● Comparison （ Sep. 10: No optimized operation, Sep. 11: Optimized operation ） 【 Boundary condition of selected days ⇒ should be almost the same 】 Sep.10 ： 55.6GJ/day Sep.11 ： 55.4GJ/day Sep.10 ： 17.6 ℃ （ av ） Sep.11 ： 18.8 ℃ （ av ） 【 Energy consumption 】 11 ％ reduced Heat quantity [GJ/h] Temperature Sep. 10 (Conventional operation) Sep. 11 (Optimized) Rate of reduction [%] Gas consumption [MJ] Heat source Power consumption [MJ] Chilled/hot water pump Power consumption [MJ] Cooling water pump Power consumption [MJ] Cooling tower fan Power consumption [MJ] Sum [MJ] Gas consumption Power consumption of chiller Power consumption of cooling tower fan Power consumption of cooling water pump Power consumption of chilled/hot water pump Sep. 10 (Conventional operation)Sep. 11 (Optimized operation) Sep.10 Sep.11 Sep.10 Sep.11 13

Aleph Networks Co. 2 Case2: Optimizing control for the Heat Water Storage HVAC-R System Kansai Electric Power Co. Wakasa Branch 14

Aleph Networks Co. Target Building and Facility Outline Target Building of Verification and Outline of Facility ＜ Target building information ＞ Location: Mihama Town, Mikata, Fukui Pref. Main purpose: Office building Structure/No. of floors: SRC, 5 stories above ground and 1 below Total floor area:10,724 ㎡ Final completion: Feb ＜ Heat source/HVAC system ＞ Water thermal energy storage tank of multi- connected complete mixing type (22 tanks, 700m3) Air-cooled heat pump chiller （ 223kW ） → HP-1 Water-cooled chiller(189kW) → R-1 Air-conditioning system: single duct + VAV system Cooling tower Air-sourced heat pump Heat exchanger HVAC on each floor Office/meeting room Refrigerator for cooling First basement level Basement pit Thermal storage tank about 700m3 Diagram of water thermal storage system (indicated temperatures are for operation in summer) (Outlet) HP-1 Type 60HP R-1 Type 60HP 15

Aleph Networks Co. Concept of Optimized Operation System ● Proposal for optimized operation of water thermal storage air- conditioning system 1)Store minimal necessary heat corresponding thermal load for the next day. 2)The heat in the tank should be used up completely by ending time of air-conditioning. 3)Complete thermal storage just before use. 4)Keep thermal storage temperature level as high as possible. Improvement of refrigerator COP Reduction of all sorts of transport power Reduction of conductive heat loss Operation control to minimize power consumption of the entire system Introduction of optimized operation control 16

Aleph Networks Co. COP = Amount of consumed energy Amount of generated heat Optimal point Image of Optimized Operation Introduction of Optimized Operation Control System Relation between outlet temp. of chilled water and COP Chilled water outlet temperature [deg C] Power consumption [kW] Refrigerator Pump Entire system 17

Aleph Networks Co. 運転最適化ブロック 目的関数：翌日１日の消費電力量 変数：冷凍機の冷水設定入口温度（ θset ） 蓄熱運転時間（ Topt ） 制約：二次側ポンプ流量等 ⇒ Forecasted load from load forecasting system Computation Flow for Optimized Operation Introduction of Optimized Operation Control System Optimized operation block Objective function: power consumption of the next day Variable: chilled water inlet temp. SP of refrigerator (θ set) Thermal storage operation time (Topt) Constraint: flow rate of secondary pump, etc. Setting of thermal storage demand Setting of outlet tem. of refrigerator Input Θ set =6.0 as an initial value Calculate operation time, Topt Calculate power consumption, pw of the entire system Determination of optimal values for θ set, Topt Storage tank Water-cooled chiller (R-1) Air-cooled heat pump chiller (HP-1) Cooling tower Heat exchanger Three-way valve Variable flow pump Constant flow pump Cooling coil (air conditioner) Fan (air conditioner) 18

Aleph Networks Co. Outline of Thermal Load Forecasting System Thermal Load Forecasting Tool of Building Outdoor relative humidity 外気比 ｴﾝﾀﾙﾋﾟ 日射量 建物情報機器情報 Forecasted thermal load ・熱負荷 ・外気温 ・外気相対湿度 ・日射量 Learning time 予測直近の実測 絶対湿度 + Operating rate of HVAC 内部発熱 Outdoor temp. 天気概況位置情報 Operating rate of HVAC Load forecasting calculation Measured DATA Forecasting time Air-conditioned zone is based on the presupposition that it is one room with uniform temp. and humidity. Thermal load Outdoor temp. Outdoor relative humidity Amount of solar radiation Location information Weather condition Internal heat generation Building information Equipment information Most recent measured absolute humidity before forecasting Outdoor enthalpy Outdoor temperature Outdoor humidity Load due to outer air inlet by air conditioner Operating rate of air conditioner Diffused solar radiation Solar radiation Direct solar radiation Reflected solar radiation Preset humidity Preset room temperature Internal heat generation 19

Aleph Networks Co. Verification of Optimized Operation Control System 1)By presetting outlet temp. of heat source on the high side, heat source COP improved. 2 ） It was possible to store minimal necessary heat for the next day and to reduce radiation heat loss. ⇒ Especially in mid season, HVAC system COP drastically improved. Introduction of Optimized Operation Control System 【 Relation between outdoor temp. and average temp. in the storage tank 】 ・ At optimized operation, storage tank temp. should be on the high side ・ The difference becomes big when the load is low （≒ low outdoor temp. ） 【 Outdoor temp. and COP improvement rate 】 Average temp. in the tank Outdoor temperature ( ℃ ) Outdoor average temperature zone ( ℃ ) COP improvement in HVAC system [%] HVAC system improvement rate At optimized operation Operation with storage full 20