Postdoctoral Fellow in R744 Primary Refrigeration Units for LHC Detector Cooling

Trondheim, Norway
19 Jun 2019
End of advertisement period
01 Jul 2019
Contract Type
Fixed Term
Full Time

About the position

We have a vacancy for a Postdoctoral Fellow within the Refrigeration research group and CERN EP-DT and EN-CV in Geneva, Switzerland on the subject of "Developing and evaluating the possible use of R744 as the primary cooling system serving the next generation of the Large Hadron Collider (LHC) detectors". The appointment has a duration of 4 years.

The Head of Department is Professor Terese Løvås. The position reports to Professor Armin Hafner.

One of the important issues for CERN is represented by the choice of the best possible primary system for the particles detector cooling systems, which must comply with stability, reliability and environmental sustainability constraints. Due to the European F-gas regulation and a global consensus (Paris COP and Kigali agreement) an adaptation of new strategies is needed to reduce the usage of fluorinated gasses. Theses fluids are widely used as working fluids in current refrigeration systems; however, due to their high greenhouse gas potential alternatives must be found.

Carbon dioxide (CO2), also called R744 when used as a refrigerant, is nowadays widely applied in commercial and industrial refrigeration applications. During the past 30 years, NTNU and SINTEF have developed various R744 systems for all kinds of applications and have a wide network within the refrigeration industry.

The background for the research work is that in the last years at CERN, CO2 evaporative cooling has been one of the favourite technologies chosen for the thermal management of tracking detectors at LHC. The ATLAS Insertable B-Layer and the CMS Pixel phase 1 upgrade have adopted it, and their systems are now successfully operational. The CERN teams are now merging the lessons learnt from these two systems in order to design and build the cooling systems for the new Upstream Tracker and the Velo upgrade in LHCb. Meanwhile, the design of the ATLAS and CMS upgrades has taken shape, and both experiments heavily rely on CO2 evaporative cooling, with cooling capacity requirements of up to 400 kW and evaporating temperature on the detector below minus 40 °C. For this application, a pumped loop is the best solution in terms of operation, temperature stability and radiation resistance requirements. The CERN teams are now working on the design of a large-scale demonstrator system, which will take into account requirements and constraints from both ATLAS and CMS. Until now the primary refrigeration system are applying conventional HFC refrigerants.

Main duties and responsibilities

The scope of the work is to develop a primary cooling system applying natural working fluids and to support the research teams at CERN responsible for the main detector cooling systems applying oil-free R744 technology.

An evaluation of cooling concepts for a primary cooling system with R744 should be done for evaporation temperatures close to the triple point of CO2 (-54°C) and a cooling capacity of up to 0.6 MW.

In addition, besides pumped circulation, an evaluation of applying R744 turbo compressor technology, as the first stage circuit, would be of interest for possible future evolution of the system. These investigations should be based on system simulation with dynamic tools like Modelica, in close collaboration with the teams at CERN.

Potential main components (technology and suppliers) are to be described and investigated.

Space considerations of the various parts of the system (underground cavern / surface location) must be considered.

A verification and validation of simulation results will be done on first pilot units.

The findings will support the modification of the specifications for the next pilot and full-scale units.

The work of the postdoctoral candidate will contain pre-design, define specifications, assist build up and assembly, verification of measurement and control devices, commissioning and performing experimental campaigns. In addition, several scientific publications are expected from the candidate.

Qualification requirements

A Postdoctoral Research Fellowship is a qualification position in which the main objective is qualification for work in academic positions. Completion of a Norwegian doctoral degree, or a corresponding foreign doctoral degree recognized as equivalent to a Norwegian doctoral degree is required.

  • The candidate should hold a PhD related to refrigeration systems and process understanding.
  • The candidate must be able to perform the required advanced system- and component simulations based on previous documented experience.
  • Expertise and experience from laboratory work related to system design, heat transfer, advanced refrigeration systems and process controls are required.
  • Excellent English skills, spoken and written, are required. Applicants from non-English speaking countries outside Europe must document English skills by an approved test. Approved tests are TOEFL, IELTS, and Cambridge Certificate in Advanced English (CAE) or Cambridge Certificate of Proficiency in English (CPE).

The appointment is to be made in accordance with the regulations in force concerning State Employees and Civil Servants and national guidelines for appointment as PhD, postdoctor and research assistant.

NTNU is committed to following evaluation criteria for research quality according to The San Francisco Declaration on Research Assessment - DORA.

In the evaluation of which candidate is best qualified, emphasis will be placed on education, experience and personal suitability, as well as motivation, in terms of the qualification requirements specified in the advertisement.

We offer

Salary and conditions

Postdoctoral candidates are remunerated in code 1352, and are normally remunerated from NOK 523 200 per annum before tax. From the salary, 2% is deducted as a contribution to the Norwegian Public Service Pension Fund. The period of employment is 4 years.

The work is performed at NTNU in Trondheim and CERN in Geneva. The latest start up time for the position is September 2019.

The engagement is to be made in accordance with the regulations in force concerning State Employees and Civil Servants, and the acts relating to Control of the Export of Strategic Goods, Services and Technology. Candidates who by assessment of the application and attachments are seen to conflict with the criteria in the latter law will be prohibited from recruitment to NTNU. After the appointment you must assume that there may be changes in the area of work.

General information

A good work environment is characterized by diversity. We encourage qualified candidates to apply, regardless of their gender, functional capacity or cultural background. Under the Freedom of Information Act (offentleglova), information about the applicant may be made public even if the applicant has requested not to have their name entered on the list of applicants.

Questions about the position can be directed to Professor Armin Hafner, Please note that applications should not be sent to this email address.

About the application:

Publications and other academic works that the applicant would like to be considered in the evaluation must accompany the application. Joint works will be considered. If it is difficult to identify the individual applicant's contribution to joint works, the applicant must include a brief description of his or her contribution.

Please submit your application electronically via with your CV, diplomas and certificates. Applicants invited for interview must include certified copies of transcripts and reference letters. Please refer to the application number IV-193/19 when applying.

Application deadline: 01.07.2019

NTNU - knowledge for a better world

NTNU - knowledge for a better world

The Norwegian University of Science and Technology (NTNU) creates knowledge for a better world and solutions that can change everyday life.

Department of Energy and Process Engineering

We conduct research and teaching covering the entire energy chain, from resources to the end-user. We look at how energy is produced and used by humans and machines in a sustainable way with regard to health, climate change and the resource base. The Department of Energy and Process Engineering is one of eight departments in the Faculty of Engineering.

Deadline: 1st July 2019
Employer: NTNU - Norwegian University of Science and Technology
Scope: Fulltime
Duration: Fixed Term
Place of service: Geneva, Switzerland; Trondheim, Norway

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