Research and development of innovative energy-saving controls for multi zone heat pump p system for buildings

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1 ICR215 WORKSHOP 1 Research and development of innovative energy-saving controls for multi zone heat pump p system for buildings Shinichi KASAHARA* (Speaker) Masafumi HIROTA**, Yoshinari IWATA***, Ichiro SAKURABA, Katsuaki NAGAMATSU Koichi SHINAGAWA****, Hiromasa KATSURAGI, Hideaki HOSHINO Masahiro OKA*, Tomohiro YABU* *DAIKIN INDUSTRIES, LTD, **Mie University, ***Chubu Electric Power, Co. Inc., ****NIHON SEKKEI, INC August 19,215

2 2 Contents t 1. Objectives/Targets 2. Features of Developed/Developing Systems 3. R&D Technologies 4. Next step for Commercialization

3 1. Objectives/Targets 1.1.Background 1 3 In an office building, energy usage for air conditioning system amounts to 3 % - 4 % of its total t energy consumption. Development of air conditioning systems with higher efficiency is strongly demanded for the energy-saving of buildings. NEDO: R & D project on Next-generation Heat Pump Systems, which aimed to increase COP by 1.5 times higher than the conventional systems. (21 213) This presentation describes the development of a new controller for the VRF system which was conducted as a part of this NEDO project.

4 Time of appearan nce [h/year] 1.2.Background Less than 5% heat load ratio COP ratio [-] 1.5 Degradation of COP in low heat load ratio Heatload ratio [%] Heatload ratio [%] Actual operating state of A/C measured in the office building Variation of COP of VRF system vs. heat load ratio Air conditioning systems in commercial buildings are mostly operated under less than 5% heat load through the year. COP of the conventional VRF systems becomes lower under low heat load conditions. In order to achieve the actually effective energy saving of the VRF system, it is important to improve its performance under the low heat load condition. 4

5 1.3.Purpose of this R&D project 5 Development of a new A/C controller that can improve the energy efficiency of the VRF system operated under low heat load condition. Evaluation of the performance that annual average COP with the new A/C controller is more than 1.5 times as high as that with the conventional one, by (1) Part-load performance tests in the test facility (2) Field test in an actual office building

6 2. Features of Developed/Developing Systems 2.1.Features of the new A/C controller 6 Room temperatur re [degc] (a) Conventional A/C controller T1 T2 Compressor Speed Time [min] Com mpressor spee ed [rps] Room temperatur re [degc] T1 (b) New A/C controller T2 The compressor operates continuously Compressor Speed Time [min] Comparison of operating states of compressor under low heat load Due to the mismatch between the capacity and the heat load, the compressor repeats startup/shutdown operations, then COP gets worse As the above figures, the new A/C controller optimizes the capacity in response to the heat load predicted from the trend of room temperature variation etc. Model d lpredictive i control is applied to the new A/C controller appearance [h/year] Time of Improved new controller Com mpressor spee ed [rps] conventional.5 controller Heat load ratio [%] COP/Time appearance vs. heat load ratio 1 COP ratio [-]

7 2.2.Other technology to improve performance of VRF New A/C controller: (1) Minimization of the heat loss in the outdoor heat exchanger in heat recovery operation (2) Minimization of the standby energy consumption (3) Reducing the energy consumption of fan motors of outdoor unit by optimizing outdoor unit fan speed (4) Reducing the energy consumption of fan motors of indoor units by using DC fan motors (5) Reducing the energy consumption of fan motors of indoor units by fan off control during thermo-off 7

8 3.R&D Technologies 3.1. Organization of R&D NEDO 8 NIHON SEKKEI, INC Chubu Electric Power, Co. Inc. Mie University 1. Selection of a building for field test and development of energy simulation of it 3. Field test 4. Improvement of the models of BEST* Estimation of heat load 2. Part-load performance tests in test facility 3. Field test Performance test and analysis 2. Part-load performance tests in test facility 3. Field test Performance analysis * Building Energy Simulation Tool by institute for building environment and energy conservation(ibec) [Co-Researcher] DAIKIN INDUSTRIES, LTD 1. Selection of a building for field test and development of energy simulation of it 2. Part-load performance tests in test facility 3. Field test Control for VRF / Analysis 8

3.2. Methods of R&D Specifications of the tested air conditioning system Type of VRF Capacity(C/H) Number of IU Air processing

1.5 times as high h as that t with Air handling Ai h dli unit unit the conventional one by part-load AE unit Room for

controller + AC motor indoor fans new controller + AC motor indoor fans Heat recovery VRF: conventional controller + AC motor

indoor unit Room2 for indoor unit AE unit Chamber Chamber 9 Air handling outdoor unit Indoor unit Outdoor unit Connecting pipe

9 3.2. Methods of R&D Specifications of the tested air conditioning system Type of VRF Capacity(C/H) Number of IU Air processing 45/5kW 2 Heat recovery 56/63kW 5 Evaluation of the performance that annual average COP with the new A/C controller is more than 1.5 times as high h as that t with Air handling Ai h dli unit unit the conventional one by part-load AE unit Room for performance tests in test facility Combination of A/C controller and indoor fan motors: Outdoor-air processing VRF: conventional controller + AC motor indoor fans new controller + AC motor indoor fans Heat recovery VRF: conventional controller + AC motor indoor fans new controller + AC motor indoor fans new controller + DC motor indoor fans Cooling mode eating mod de H Room1 for indoor unit Room2 for indoor unit AE unit Chamber Chamber 9 Air handling outdoor unit Indoor unit Outdoor unit Connecting pipe Indoor unit Exterior of test facility (Chubu Electric Power) Air handling unit Air flow Schematic of testing rooms for A/C (for heat recovery VRF)

3.2. Methods of R&D Field tests were conducted in the one floor

COP using the new A/C controller is more than 1.

control : Dec, 21~Nov, 211 New control : Jan, 212~Dec, 212 1 Only

were used Air processing VRV unit Heat recovery VRV unit

air Waste heat Outdoor unit Indoor unit Heating CoolingHeating

10 3.2. Methods of R&D Field tests were conducted in the one floor of the office building in Nagoya to evaluate that annual average COP using the new A/C controller is more than 1.5 times as high as that with the conventional one Conventional control : Dec, 21~Nov, 211 New control : Jan, 212~Dec, Only the new controller was implemented Same indoor and outdoor units were used Air processing VRV unit Heat recovery VRV unit Capacity(C/H) 45/5kW 1/112kW Number of IU nd floor Fresh air Waste heat Outdoor unit Indoor unit Heating CoolingHeating Waste heat Outdoor unit floor space 6 m 2 Office building and reference floor used for field tests

11 3.3.Detail of the developed controller Capacity is optimized by the combination of the real-time prediction of the indoor heat load using model predictive control and the capacity characteristics ti of the heat exchanger of the indoor units. Then, optimum combination of the indoor fan speed and target Te/Tc are calculated. 11 Indoor unit Required capacity (1)Room temperature model C a p V r dt dt r Q hex Q i Q o Trend of room temperature Outdoor unit (2) Heat exchanger model Q f T, T, T, SH, SC, hex Optimum fan speed & Te/Tc r e c (3)Fan speed control SendTe/TctoOU cooperative control (4) Select Te/Tc from the targets of Te/Tc from all indoor units (5) Compressor speed control

3.4.Results of the study (Part-load Tests) How to calculate annual average COPs The annual average COPs of the VRF systems were calculated by combining the results

year. COP surfaces COP 1 9 8 7 6 COP 5 4 3 2 1 2 25 3 35 外気温度 [ ] + Outdoor temp. 1 8.8.6.4.2 冷房負荷率 Cooling load ratio 12 9-1 8-9 7-8 6-7 5-6 4-5 3-4 2-3 1-2 -1 Cooling load ratio 1 9.

12 3.4.Results of the study (Part-load Tests) How to calculate annual average COPs The annual average COPs of the VRF systems were calculated by combining the results of part-load performance tests and the time (hours) of appearance of heat load ratio and outdoor temperature that had been measured in the office building through a year. COP surfaces COP COP 外気温度 [ ] + Outdoor temp 冷房負荷率 Cooling load ratio Cooling load ratio Outdoor temperature Time of appearance of heat load ratio and outdoor temperature in a year

13 3.4.Results of the study (Part-load Tests) CO OP [-] Conventional New (AC fan) New (DC fan) Cooling Heating Annual Air processing VRF Cooling Heating Sim. Annual Total Heat recovery VRF Seasonal / annual average COPs on part-load performance test 13 The Annual Average COP with the new controller + AC fan can be achieved 1.3 times as high as the COP with conventional one. The Annual Average COP with the new controller + DC fan can also be achieved 1.71 times as high as the conventional one. Annual average COPs predicted d based on part-load performance tests Annual average COPs Increase ratio of annual average COPs A/C controller Air processing Heat recovery Total Air processing Heat recovery Total Conventional Base Base Base New + AC fan % 38% 3% New + DC fan % 18% 71%

14 3.4.Results of the study (Field Tests) COP [-] Mont thly average Air processing VRF Conventional Heat recovery VRF 4. Total controller COP [-] Mont thly average Air processing VRF Heat recovery VRF Total 14 New controller + AC motor fans.. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Monthly average COPs measured in the office building for two years Field measurements in the actual office building in two years: 12/21 ~ 11/211: Conventional controller 1/212 ~ 12/212: New controller with AC motor indoor fans COP increased by 31% The new controller can show its full energy-saving performance with the DC motor indoor fans. COPs with the new controller + DC motor indoor fans were estimated t based on the results of the part-load performance tests.

3.4.Results of the study (Field Tests) 6 5 Conventional New (AC fans) fan) New (DC fans) fan) 15 COP [-]

fans (cooling) Comparison of annual and monthly average COPs measured in the actual office building

COPs A/C controller Air processing Heat recovery Total Air processing Heat recovery Total Conventional 2.

15 3.4.Results of the study (Field Tests) 6 5 Conventional New (AC fans) fan) New (DC fans) fan) 15 COP [-] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual COP increase ratio by use of the DC motor fans (cooling) Comparison of annual and monthly average COPs measured in the actual office building Annual average COPs in the actual office building Annual average COPs Increase ratio of annual average COPs A/C controller Air processing Heat recovery Total Air processing Heat recovery Total Conventional Base Base Base New + AC fan % 36% 31% New + DC fan % 96% 69%

16 3.5.Achieved outcome 16 Total Plan Development of a new A/C controller that can improve COP of VRF systems under low heat load condition Research Items (1) Develop of an energy simulation to estimate the effect of the new A/C controller (2) Part-load test in the facility (3) Field test in the actual building Final Goal Technologies Level at the beginning Attained level 1.5 times higher Annual average COP Annual average COP annual average COP =2.28 = /2.28=1.69 Final Goal Estimation of performance of the new controller and the possibility of 1.5 times higher COP Evaluation of possibility of 1.5 times higher COP from the measurement data in the facility Evaluation of 1.5 times higher h COP from the measurement data in the filed test Technologies Level at the beginning There were some energy simulation such as LCEM, but not include simulation of controllers Attained level The goal had been achieved Annual average COP Annual average COP = = /2.14=1.71 Annual average COP Annual average COP =2.28 = /2.28=1.69 (4) Improvement of To make a proposal of model There was no proposal from the The goal had been models of BEST achieved improvement of BEST than can improve accuracy of estimation of heat load to BEST committee measurement data in facility tests and field tests

17 4.Next step for Commercialization 4.1.New VRF products New VRF products VRV X with the new controller have been launched since March, 215 in Japan by DAIKIN INDUSTRIES. These products will be launched to overseas market in the future, and the new controller also will be applied to other VRF systems, such as heat recovery VRF systems etc. 17 VRT* Smart control *variable refrigerant temperature Ceiling- mounted round flow cassette Ceiling mounted 2-way flow cassette VRV X outdoor unit (heat pump, capacity range: kw) VRV X products Ceiling mounted Ducted concealed ceiling unit 1-way flow cassette VRV X indoor unit

18 4.2.Estimation of energy-saving effect 18 Number of VR RF stocks in Japan J (x1 3 ) Existing VRF systems stems New VRF systems using the new contoroller (year) Prediction of the number of VRF system stocks in Japan Energ gy consumption n of all VRFs in Japan (GWh) Energy consumption using new VRF systems Energy saving in crude oil equivalent Energy consumption using conventional VRF systems (x1 4 kl) (year) Prediction of energy-saving effect using the new controller Energy-saving will increase 2977GWh/year (76.57kL/year in crude oil equivalent) at 23. Assumption 1) Diffusion of new VRF systems will be as fast as that of existing VRF systems. 2) Renewal cycle of VRF systems is 13 year. 3) The capacity of VRF systems and the amount of heat load referred from typical buildings in Japan crude oil equ uivalent rgy saving in Ene

19 19 Thank you very much for your kind attention!

Development of high efficiency VRF systems under partial heat load for commercial buildings

Development of high efficiency VRF systems under partial heat load for commercial buildings Kousuke KIBO*, Masafumi HIROTA**, Yuta TERANISHI**, Yoichi MIYAOKA***, Katsuaki NAGAMATSU*** and Takashi NAMIWO***