Publications related to Free cooling

Selection and Optimal Use of Nanoporous Materials for Adsorption Energy Technologies

Due to the large waste of heat in the power and industrial sectors, our use of energy is inefficient. Moreover, it relies on rapidly depleting and greenhouse-gas-emitting sources such as fossil fuels. While the scarcity of energy resources is a relevant so ...

EPFL2023

Operational Map And Thermal Performance Of A Thermosyphon Cooling System For Compact Servers

John Richard Thome, Jackson Braz Marcinichen, Filippo Cataldo, Raffaele Luca Amalfi

This paper advances the state-of-the-art in novel passive two-phase systems for more efficient cooling of datacenters and telecom central offices compared to the traditional air-based cooling solutions (e.g. aisle-based containment systems). The proposed p ...

AMER SOC MECHANICAL ENGINEERS2021

Multi-Objective Management of Multiprocessor Systems: From Heuristics to Reinforcement Learning

Arman Iranfar

In my thesis, I reveal several already-existing and emerging challenges in multi-objective management of multiprocessor systems, and address them through novel solutions, from heuristics to RL, depending on the complexity of the problem. Conventional multi ...

EPFL2020

Enhancing Two-Phase Cooling Efficiency through Thermal- Aware Workload Mapping for Power-Hungry Servers

David Atienza Alonso, Marina Zapater Sancho, Arman Iranfar, Ali Pahlevan

The power density and, consequently, power hungriness of server processors is growing by the day. Traditional air cooling systems fail to cope with such high heat densities, whereas single-phase liquid-cooling still requires high mass flowrate, high pumpin ...

IEEE and ACM Press2019

A Modular Timber Construction System for the Sustainable Vertical Extension of Office Buildings

Sophie Lufkin, Emmanuel Rey, Aleksis Dind

Most European cities are facing urban densification issues. In this context, a solution to create usable spaces without additional pressure on land consists in the vertical extension of existing buildings. Given their abundance in the building stock, terti ...

2018

A data-driven model for the air-cooling condenser of large-scale coal-fired power plants based on data reconciliation and support vector regression

François Maréchal, Ivan Daniel Kantor, Ligang Wang, Jean-Loup Sylvain Robineau, Xiang Li

The performance of a direct air-cooling condenser under operation is rather complicated, as it is interactively affected by the operating conditions (e.g., the mode of air fans) and ambient conditions (e.g., temperature and wind speed). To understand the c ...

2018

Identification of optimal operating strategy of direct air-cooling condenser for Rankine cycle based power plants

François Maréchal, Ligang Wang, Xiang Li

Direct air-cooling condenser has attracted significant attention in the last decade due to the employment of Rankine-cycle based power plants from renewable (e.g., concentrated solar) or traditional (e.g., coal) heat sources in water-scarce areas. The opti ...

2018

Small, High-Speed, Oil-Free Radial Turbo-compressors for Cooling Applications: Refrigerant Selection

Jürg Alexander Schiffmann

Emerging energy-efficient, oil-free radial centrifugal compressors seem promising for small to mid-capacity air conditioning and refrigeration applications. Compressor design must balance trade-offs among impeller diameter, bearing type, and refrigerant se ...

2018

District heating and cooling energy network using CO2 as a heat and mass transfer fluid

François Maréchal, Daniel Favrat, Luc Girardin, Samuel Henchoz

The 5th generation compact district heating and cooling networks in a temperature range of 10 to 16 °C have a great potential for energy savings by providing a heat source for decentralized heating heat pumps, a cold source for air-conditioning and a heat ...

2018

Working Space – An innovative modular timber construction system for the sustainable vertical extension of office buildings

Sophie Lufkin, Emmanuel Rey, Aleksis Dind

Urban densification issues are one of the key challenges for most European cities. In this context, the vertical extension of existing buildings provides a solution to create usable spaces without wasting additional land. Little attention has been given to ...

2017

Integration of CO2 networks and Power to Gas for emerging energy autonomous cities in Europe

François Maréchal, Luc Girardin, Raluca-Ancuta Suciu

CO2 is used more and more as a refrigerant in the commercial and food retail industries and a majority of experts believe that its share in the field of residential heating, commercial refrigeration and mobile air conditioning across Europe will be higher ...

2017

Multi-objective optimization of utility systems and heat exchanger networks: method and application to the solar assisted hydrothermal gasification case

François Maréchal, Alberto Mian, Adriano Viana Ensinas, Emanuele Martelli

This work presents a novel framework for the multi-objective synthesis of utility systems and Heat Exchanger Networks (HEN) under single or multi-period operations. In order to solve the resulting Mixed Integer Non Linear (MINLP) programming problem, a bi- ...

Elsevier Science Bv2017

Physical effects of thermal pollution in lakes

Alfred Johny Wüest, Damien Bouffard

Anthropogenic heat emissions into inland waters influence water temperature and affect stratification, heat and nutrient fluxes, deep water renewal, and biota. Given the increased thermal stress on these systems by growing cooling demands of riparian/coast ...

American Geophysical Union2017

Potential of refrigerant based district heating and cooling networks

Samuel Henchoz

Urban areas represent an ever increasing challenge in terms of energy use and environmental impact associated with it. Projections from the United Nation expect this number to reach 66% by 2050. In Europe 40% of the final energy consumption and 36% of the ...

EPFL2016

Key Energy and Technological Aspects of Three Innovative Concepts of District Energy Networks

François Maréchal, Daniel Favrat, Samuel Henchoz, Patrick Chatelan

Energy needs in urban areas are heterogeneous by their nature, spatial distribution and temperature level required. Three concepts of district energy networks that could provide the energy services efficiently to a city centre are compared. The focus is on ...

2016

Towards energy-autonomous cities using CO2 networks and Power to Gas storage

François Maréchal, Paul Michael Stadler, Araz Ashouri, Raluca-Ancuta Suciu

Under Energy Strategy 2050, the federal government of Switzerland plans to greatly reduce per capita energy consumption, decrease the share of fossil fuels, and replace the nuclear electricity generation by gains in efficiency and use of renewable energy s ...

2016

Thermal-hydraulic modeling of a novel HTS CICC for nuclear fusion applications

Pierluigi Bruzzone

A thermal-hydraulic model has been developed for the novel cable-in-conduit conductor (CICC) recently proposed by ENEA, which foresees the use of 2nd Generation REBCO-based Coated Conductor tapes stacked into twisted grooves slotted into an Al core. A cent ...

IEEE Institute of Electrical and Electronics Engineers2016

Theoretical Study of a Novel Oil-Free Co-Rotating Scroll Compressor Integrated into a Hybrid Absorption Heat Pumps

Jürg Alexander Schiffmann, Luis Carlos Mendoza Toledo

Hybrid absorption heat pumps (Osenbrück cycle and Hybrid wet compression cycle) are known for high temperature lifts, low-pressure ratios and wide capacity control. They are well suited for processes with the occurrence of significant heat sink and heat so ...

2016

Key energy and technological aspects of three innovative concepts of District energy networks

François Maréchal, Daniel Favrat, Samuel Henchoz, Patrick Chatelan

In urban areas, the use of thermal energy services is intensive and relatively heterogeneous by their nature, spatial distribution and temperature level required. In this study three concepts of district energy networks that could provide these services ve ...

2015

Performance of novel ventilation strategy for capturing CO2 with scheduled occupancy diversity and infiltration rate

Moon Keun Kim

This paper proposes a novel ventilation strategy for capturing CO2 with scheduled occupancy diversity, and changes in recirculating ratio and infiltration rate. While many publications have described filters and a lamp that can efficiently capture and remo ...

Pergamon-Elsevier Science Ltd2015