Technical Presentations

• Impact of the Substrate Design on the Evaporative Cooler Performance (Amel Boudjabi, Algeria)

The presentation introduced the performance of an evaporative cooler, with an aluminium plate covered of a water film used as the substrate material for the heat and mass transfer between the dry product air and the wet working air. There are three different configurations for the substrate surface, a flat plate, a corrugated surface on the two sides, a corrugated surface with more water injection. The study found the wavy design is meaningful in terms of heat surface increase which allow to reach lower product temperatures but it causes an increase in the pressure loss. And other investigations will determine how can we fix the problem of pressure loss and how to optimise the water consumption.

• Overview of Research & Development Work on IEC: M-cycle Technique (Muzaffar Ali, Pakistan)

The presentation introduced an overview of different research activities which we did in in that preparative cooling, especially about the materials, configurations of M-cycle and performance assessment. And gave another view of different integrated system which they developed in last few years. The key objectives of research work are design of innovative indirect evaporative configurations, utilization of efficient materials with high wettability, development of multiple design variants (DVs) and real-time system assessment through experimental testing. For integrated solar air cooling system with desiccant coated channels, optimize integrated system from various aspects like materials, watering channel length, channel gap sizes, channel height, airflow rate, and airflow ratio, achieving high dew-point effectiveness near to 1.

• Data Center cooling systems optimization and IEC/DEC processes application (Xiaoyun Xie, China)

The presentation introduced a field test of two data centers, optimization of cooling system parameters and research on cooling performance in different areas. The test found some problems in system: hot and cold air mixing in the server room, simultaneous humidification and dehumidification, poor cooling water quality, affecting plate exchange and cooling tower heat transfer, increasing resistance. After optimization by increase chilled water temperature difference, 20-30% reduction in cooling system energy consumption and 15-25% reduction in cooling system costs. And the higher the chilled water temperature difference, the lower the CLF and the higher the free cooling rate in different areas.

Report 1: Real cases collection

• Denmark group (Alireza Afshari)

In Denmark, both DEC and IEC systems are used, though their applications are less common compared to other cooling methods due to the country’s relatively temperate climate. The challenges of implementing evaporative cooling technologies may include following:

Inefficiency in Cooler Climates; Increased Humidity (for DEC); High Installation and Maintenance Costs; Underutilization; Alternative Cooling Technologies; Environmental Considerations

• China group (Jiale Fan)

Introduced a case: indirect water chillers applied in a data center in Xinjiang, China

The cooling system using IEC water chillers as the natural cooling source to deliver cold instead of compression refrigerating machine throughout the year.

In the field test in 2021, 6 IEC water chillers are operating. The wet-bulb efficiency is about 120%. The second field test was conducted in 2023, while the IT load rate increased from 5.8% to 44.1%. The wet-bulb efficiency is 152.8%. The measured PUE value decreased from 1.877 to 1.286.

Problems: Low IT load and excessive equipment selection result in high PUE of the data center. The energy consumption associated with the air conditioners in Data Center is high. The energy consumption of cooling water pumps is higher than chilled water pumps.

• Spain group (Manuel Ruiz de Adana)

Real cases ——RACU

RACU system was tested under real conditions for a classroom at University of Cordoba (Spain) under South European Climate Weather conditions. The RACU prototype allows to independent control of indoor air temperature, indoor air humidity and indoor air CO2, level in a real classroom. For this work only the DIEC operated, the desiccant wheel was not activated due to low indoor humidity. High EER and DEER values were obtained specially under outdoor conditions with high dry air temperatures and low outdoor humidity ratio.

• Discuss

Give more detail analysis in collected cases, and answer some uniform question in different cases. and show which technology people used in different countries. The focus of report needs to confirm, like focus on efficiency, water consumption and environment issues, recommended length of each case study is about 15-20 pages, the detail data can be added in the appendix. The maintenance cost related to legionella treatment and control need to be discussed.

Report 3: Performance analysis

• Italy group (Stefano De Antonelli)

Introduced the contents of performance analysis report, including introduction, DEC air coolers, IEC air coolers, DEC/IEC water chillers.

Introduction: presents and discusses the various technologies that can be used for direct and indirect evaporative cooling.

In each process, need to introduce system description, performance indicators and power consumption.

• Spain group (Francisco Comino)

A regenerative indirect evaporative cooling (RIEC) system has been analyzed under laboratory conditions. A Design of Experiments was performed for this analysis.

l High cooling capacity was achieved with the RIEC system, up to 17kW. The energy consumption of the system was very low, between 0.4 kW-1.2kW.

Therefore, high Energy Efficiency Ratio values were achieved, up to 26.

• China group (Ce Zhao)

Summer performance of IEC water chillers in a data center in Changji: Volume mass transfer coefficient of paddings equals 6292kg/h/m3. The COP of water chiller is 7.72.

Winter performance of IEC water chillers in a data center in Yanggao: In field test, the lowest air temperature outside is -24.8°C. IEC water chiller works automatically and safely.

Testing performance summary of IEC water chiller and components: heat transfer coefficient of air cooler in Changji equal 23.8W/(m2*K), in Yanggao equal 37.6W/(m2*K).

Report 2: Feasibility analysis

• China group (Xiaoyun Xie)

Introduced the feasibility analysis report, including the importance of analyzing feasibility, the definition of feasibility, and methods for determining feasibility. And four countries were selected to calculate the feasibility of evaporative cooling technology in them.

• France group (Chadi Maalouf)

Introduced the feasibility of evaporative cooling in three cities in France.

• Spain group (Francisco Comino)

Experimental results and a mathematical model were used to perform the feasibility analysis of a RIEC system under Spanish climatic conditions.

The values of supply air temperature, dehumidification, ventilation and cooling air flow rates, and dew point efficiency were obtained for each climatic condition.

The results showed that the dew point efficiency values increased for warm and dry weather conditions.

• Belgium group (Alanis Zeoli)

The feasibility of evaporative cooling of ten climatic zones have been selected to be studied. Figure illustrates the ten climatic zones and the corresponding cities. The climate types range from 0A to 6A, based on the ASHRAE climate zone classification.

• Discuss

We could reference with this climate conditions from the ASHARE classification, we could also consider our results that feasible region and partly feasible region. Maybe it is a little different with the ASHARE classification. And feasibility forecasting of future climate condition is also important.

Report 4: Simulation analysis

• Belgium group (Alanis Zeoli)

Introduced the structure of the simulation analysis report. Including introduction, simulation boundary conditions, modeling and simulation of DEC/IEC components, modeling of equipment, simulation of case studies and guidelines and conclusions. It is necessary to introduce device modeling and control strategies, and calculate key performance indicators: component level, equipment level and system level.

• China group (Jiale Fan)

Introduced three model of IEC system and give simulation results in typical working conditions and variable working conditions. Series and parallel IEC water chiller modeling using EES, IEC air cooler modeling using MATLAB. At the same typical working conditions, wet-bulb efficiency of parallel IEC water chiller is higher than series IEC water chiller.

• Spain group (María Jesús Romero-Lara)

Using modeling simulation, seasonal analysis comparison of three air-cooling systems in terms of thermal comfort, air quality and energy consumption for school buildings in Mediterranean climates.

The DIEC system achieved more unfavorable thermal comfort conditions than the DX and RACU for Lampedusa since the air supply humidity was no controlled. The air-cooling system with the longest period in favorable air quality conditions was the DIEC system for all climatic zones, due to the high outdoor air flow rates that was supplied to the classroom. The systems with the lowest energy consumption were the DIEC and the RACU. Regarding environmental impact, the DIEC and the RACU could be an alternative to DX systems to reduce CO, emissions in the warmest zones.)

Discussion

• Each group in this Annex responsible for different parts of final reports.

	Report I: Real cases collection	Report 2: Feasibility analysis	Report 3: Performance analysis	Report 4: Simulation analysis
Belgium	1~2 application cases, IEC air coolers, 1, finished, 2nd, 31st May, 2025 28th, February, 2025 (Questionnaire collection)	Analysis of IDCs system, (finished) Oct, 1st, 2024	Cooling water, January, 31st, 2025 IEC air cooler, March, 31st, 2025 Outline. (send by Stefano, 5th, November, 2024)	Simulation tool, April, 2025 Desiccant cooling, IEC air coolers, Dec, 1st, 2024, modeling Outline. (send by Vincent, 31st, October, 2024)
China	A review of all projects, 2~3 in detail, 1, modified, July,1st, 2nd, 3rd, Dec, 1st, 2024 28th, February, 2025 (Questionnaire collection)	IEC/DEC technologies under China weather conditions, Dec 1st, 2024 Future feasibility (April, 15th, 2025)	IEC water chiller performance, Dec, 1st ,2024 Outline. (send by Stefano, 5th, November, 2024)	IEC water chiller, modeling, EES, matlab, simulation results Dec, 1st, 2024
Denmark	1 application case, 1, small modification, Dec, 1st, 2024 Questionnaire, 15th, November, 2024 (sending to all) 28th, February, 2025 (collection)	Cooperated with Belgium group	Review the report	Review the report
France	1 possible case Dec, 1st, 2024 28th, February, 2025 (Questionnaire collection) Review the report	IEC regenerative coolers, EC air coolers system, France. January 1st, 2025 Future forecasting feasibility Climate data (December 1st, 2024) Analysis (April, 15th, 2025)	Review the report	IEC regenerative coolers, modeling using EES, SPARK, January, 31st, 2025
Italy	28th, February, 2025 (Questionnaire collection) Review the report	IEC applied in Data centers, IEC air coolers, January, 31st, 2025	Introduction, IEC/DEC air coolers, lab testing, Draft, 5th, November, 2024	Verification of data with simulation result, Desiccant wheel, IEC air cooler, review work, January, 31st, 2025 Review the report
Spain	1 case, Dec, 1st, 2024 28th, February, 2025 (Questionnaire collection)	IEC regenerative coolers, applied in Spain climate conditions. January, 31st, 2025	IEC regenerative coolers, lab testing, 28th, February, 2025 Outline. (send by Stefano, 5th, November, 2024)	Transys modeling for IEC air cooler, simulation results, Desiccant combined with IEC, comparison,  March, 31st, 2025
Draft deadline	May, 1st, 2025	May, 31st, 2025	May, 1st, 2025	March, 31st, 2025

 

Schedule of the next activities

• Schedule
  • The next workshop 1 will be face-to-face meeting, is planned to be carried out in April 2025, Cordoba, Spain, the detail arrangement would be discussed with everyone.
  • The next workshop 2 will be face-to-face meeting, is planned to be carried out in October 2025, Beijing, China, the detail arrangement would be discussed with everyone.
  • Organizing an international conference of IEC/DEC technologies, Beijing, China, October (20^th ~22^th), together with the second workshop of 2025.
  • Focus of each report, clearly giving the main points and main problems to be solved, make sure the typical model and the indicators used in process analysis, give the draft of final report, discussion through email.
  • Push possible co-research publications between participants.
  • Prepare publications and reports, organize the writing of the final reports of Annex 85.

 

• Activities
• Cooperation publications organization
• Feasibility analysis, 4 cooperation publications have been prepared;

1. Methodology, Feasibility analysis using indicators method, China group, France group, Spain group, Italy group, Belgium group.
2. Feasibility analysis of IEC/DEC in France, France group, China group
3. Feasibility analysis of IEC/DEC in Spain, Spain group, China group
4. Feasibility analysis of IEC/DEC in Italy, Italy group, China group
5. Feasibility analysis of IDC system, Belgium group, Denmark group

• Performance analysis:
  • Performance analysis of IEC air coolers, IEC water chillers
• Real cases collection:
  • Different real projects using IEC/DEC technologies
• Simulation analysis

 

• Future actions:
  • Reviewers in EBC Exco committee will be recommended in November, 2024, on the Exco meeting.
  • Apply 6 months extension of Annex 85 on EBC meeting, in November, 2024.
  • Online meeting, after collection of reports, on about 15^th December,2025.
  • Reviewers of Annex groups, finish reviewing at the end of February.
  • Draft edition of the final reports, better to be finished before the end of April, submit to a folder set up in Teams.
  • Xiaoyun and China group will be responsible for the checking and integrating of all reports, and then send to the EBC Exco members for their reviewing, before July.
  • The four parts of final reports will be combined to a book “Indirect Evaporative Cooling Technologies”, editing work mainly afforded by China group, and assisted by other groups.
  • Cooperation publications organization
  • An ISO standard is now under applying through ISO TC 86 Refrigeration and Air Conditioning.

Contact information

 

• Chadi Maalouf

           Chadi.maalouf@univ-reims.fr

• Tala Moussa

           tala.moussa@univ-reims.fr

• Xiaoyun Xie

xiexiaoyun@tsinghua.edu.cn
Building Energy Research Center, Tsinghua University, Beijing, China.

• Yijie Liu

liuyijie19@mails.tsinghua.edu.cn
Building Energy Research Center, Tsinghua University, Beijing, China.

• Jiale Fan

fjl22@mails.tsinghua.edu.cn
Building Energy Research Center, Tsinghua University, Beijing, China.