PhD position OT-21945

Development of innovative diurnal radiative cooler for dew water recovery

92160 ANTONY

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.

Interns (or doctoral students, or contract workers, etc.) hosted at INRAE, a public research establishment, are subject to its internal regulations, particularly with regard to the obligation of neutrality and respect for the principle of secularism. As such, in the exercise of their functions, whether or not they are in contact with the public, they must not demonstrate their convictions, through their behavior or dress, whether religious, philosophical or political. »

 

Work environment, missions and activities

Resume

With carbon costs increasing due to climate change, cold production is a process that also makes  possible to dehumidify air and recover water. Dew collectors, based on the principle of radiative cold in nighttime conditions, have been the subject of numerous studies and recent work focuses on the extension of this process to daytime conditions. The objective of this thesis is to develop a prototype daytime radiative cooler, by equipping an existing nighttime device with a solar reflector. The aim of the work is to document the operation and efficiency of this water recovering process, depending on the climate, and to optimize its architecture with an Eco-design approach. The process will be compared with conventional cold production processes in order to estimate the carbon emissions savings of the passive solution. Thus, we will seek to develop a resilient and ecological method of producing cold for water recovery.

 

Keywords :

Radiative condenser, reflexive and emissive materials, hydrophilic matrix, water and air moisture management, solar still

 

Mission and activities:

 

* Context of the thesis project

The thesis is part of the 3D-Stellar project which aims to treat effluent from olive oil production to extract drinking water and activated carbons. This project is part of a Partnership for Research and Innovation in the Mediterranean Region (PRIMA), which involves laboratories from Mediterranean partner countries and two French laboratories, whose work is coordinated by the University of Lorraine around a solar still concept.

 

* Method

Radiative cold is produced by radiative exchange between an object and the celestial vault, characterized by a sky temperature, lower than the ambient and dependent on cloud cover. Radiative exchange takes place in the infrared wavelength range. Its consequences are easily observed at night, but the exchange persists during the day, if protection against solar radiation is sufficient. An important part of the work lies in the experimental development of a daytime radiative cooler. Starting from an existing nocturnal device, it will be necessary to develop a reflector to protect the system from solar radiation. Outdoor instrumented tests, night and day, will document functioning of the prototype. In conjunction with the technical team of the laboratory, we will develop in the thesis a celestial vault simulator, which will be coupled with a meteorological wind tunnel: this set will make it possible to broaden the test conditions and get closer to the Mediterranean conditions of the Stellar3D project. The condensation cell, inside the cooler, has also be studied to maximize the condensate collection surface through an appropriate choice of substrates and their hygroscopic properties. Finally, the work will be extended to the study of the cooling of air flow downstream of a solar evaporator. The passive cooler will be optimized by carrying out the thermoeconomic study and life cycle analysis, the results of which will be compared to active methods (thermoelectricity, gas absorption) in order to formulate energy cost criteria in relation to the benefits, which are the quantities of water collected. This step will be used to develop a model to study the coupled operation between the cooler and the solar evaporator (developed by the University of Lorraine) and select the most appropriate cold production method for the production of water with high environmental quality.

 

* expected results :

estimation of the costs of water production by cold condensation, optimal architecture of a passive cooling system, guidelines about surface treatment design for heat and mass transfer

 

* working environment:

FRISE, a research unit based in Antony (92), studies cooling and refrigeration systems for food preservation under the constraints of low environmental impact and food safety. The Enerfri research team is carrying out work on controlling energy expenditure and reducing the environmental impact of refrigeration machines. This thesis, funded by the ANR, will be directed by Stephanie Lacour and Minh Hoang, specialist in the Eco-design of refrigeration processes, within the Interfaces doctoral school (ED 573) at Paris-Saclay and the Enerfri team. Prototyping and instrumentation of the cooler will be carried out with the support of our Tecfri technical team. The work will be carried out in a wind tunnel to generating air flows at controlled speed, temperature and humidity and designed to study evaporation/condensation phenomena, with specific visualization techniques (optical and infra-red thermography).

 

 

Training and skills

Master's degree/Engineering degree

Required profile:

Training: master's degree in thermal or energy

Knowledge: heat and radiative transfers, air conditioning, English, thermodynamic

Skills: motivation for experimental work and instrumentation, ability to work in a team, interest in prototyping, desire to share knowledge

INRAE's life quality

By joining our teams, you benefit from (depending on the type of contract and its duration):

- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
parenting support: CESU childcare, leisure services;
- skills development systems: trainingcareer advise;
social support: advice and listening, social assistance and loans;
holiday and leisure services: holiday vouchers, accommodation at preferential rates;
sports and cultural activities;
- collective catering.

How to apply

I send my CV and my motivation letter
sujet_final_english.pdfpdf - 105.65 KB

Offer reference

  • Contract: PhD position
  • Duration: 36 months
  • Beginning: 01/11/2024
  • Remuneration: 2100€ gross monthly
  • Reference: OT-21945
  • Deadline: 14/06/2024
Centre Ile-de-France - Jouy-en-Josas - Antony

UR 1460 FRISE 92160 ANTONY Website

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