Energy performance comparison of ventilation-based heating versus water-based heating systems in an efficient residential building

in Fluid Dynamics & Material Processing (in press)

The application of air-based heating systems as a possible approach to reduce the construction costs in highly efficient residential buildings is becoming popular. Air-based heating systems have been well ... [more ▼]

The application of air-based heating systems as a possible approach to reduce the construction costs in highly efficient residential buildings is becoming popular. Air-based heating systems have been well-known for their usage in passive houses during the past three decades. Available studies on such systems tend mostly to focus only on comparing exhaust air heat pump technology with conventional systems in efficient buildings. Moreover, most of the existing studies ignore the usual presence of the electrical heaters as backup. Besides, a comprehensive study and comparison between different air-based heating system concepts is still missing. In this study, four different air-based heating system concepts separated by the type of heat source of heat pump for heating and domestic hot water are defined. These systems are compared to four conventional heating system, including floor heating and direct electrical system employing dynamic annual simulations. According to simulation results, the systems with floor heating have shown the best system efficiencies and the lowest energy demand in comparison to the other systems. The main reason for this was the lower supply temperatures of the floor heating systems. Between the air heating systems, the system equipped with an outdoor air heat pump showed a better energy performance than an exhaust air system. The main reason for this could be attributed to the power limitation of exhaust air heat pump systems. [less ▲]

Theoretical Considerations about Energy Transition in Luxembourg

in Environmental Sciences Proceedings (2022)

The energy transition is a certain phenomenon in the future which as of yet has no agreed definition. It involves a shift in the dominant ‘rules of the game’—a transformation of established technologies ... [more ▼]

The energy transition is a certain phenomenon in the future which as of yet has no agreed definition. It involves a shift in the dominant ‘rules of the game’—a transformation of established technologies and societal practices and movement from one dynamic equilibrium to another, typically stretching over several generations. The study aims to explore some salient features of this transition that Luxembourg will face using a theoretical approach. The study was limited to the transportation sector, residential sector, and public dimension. it has been shown how the availability of different contextual factors in Luxembourg will raise the need for new pathways to move towards this transition. The alternative pathways have been argued, to [less ▲]

Experimental characterization of the temperature gradient inside a membrane distillation module

in Energy Reports (2022)

Characterizing the Theory of Energy Transition in Luxembourg, Part Two—On Energy Enthusiasts’ Viewpoints

in Sustainability (2021)

A three-dimensional model for the heat and mass transfer in air-gap membrane distillation

in Desalination and Water Treatment (2021)

Membrane distillation (MD) is a process to desalinate sea water. Pilot plants are operated aiming at increasing the modules’ efficiency for large-scale applications. In air-gap membrane distillation (AGMD ... [more ▼]

Membrane distillation (MD) is a process to desalinate sea water. Pilot plants are operated aiming at increasing the modules’ efficiency for large-scale applications. In air-gap membrane distillation (AGMD) the state-of-the-art modeling of mass and heat transfer is one-dimensional, combining evaporation and diffusion through the membrane and the condenser channel in one correlation. In this work, a numerical model is developed which computes AGMD modules in three dimen- sions. For evaporation and condensation, energy conservation equations at the interfaces are solved. Simulation results are compared to experimental data and a good agreement is found. The model is then employed to compare numerically two air-gap MD module configurations and evaluate their performance at different feed inlet temperatures, velocities and air-gap thicknesses. In the upside configuration, the hot feed flows above the membrane, while in the downside configura- tion it flows below the air-gap and membrane. In the latter, the feed solution is not in contact with the membrane but separated by the air-gap which is expected to improve the fouling resistance of the membrane. The three-dimensional computational fluid dynamic computation allows the visu- alization of the velocity profile in the air-gap due to buoyancy in the downside configuration [less ▲]

Literature survey of droplet entrainment from water pools

in Nuclear Engineering and Design (2021)

Field monitoring data on a residential exhaust air heat pump system (air-to-air heat pump)

in Data in Brief (2021)

This data article presents the raw data used in the article “Experimental and analytical evaluation of exhaust air heat pumps in ventilation-based heating systems” (in review). The data set contains ... [more ▼]

This data article presents the raw data used in the article “Experimental and analytical evaluation of exhaust air heat pumps in ventilation-based heating systems” (in review). The data set contains measurement results of a field monitoring on a residential exhaust air heat pump system (air-to-air heat pump) in Germany. This data could be used to investigate the dynamic behaviour and performance of the exhaust air heat pump systems. The data set contains air temperature and humidity of all four sides of the heat pump unit. Moreover, the electrical consumption of the unit and the dynamic pressure difference on the exhaust side (as indication of the air volume rate) could be also found in the data set. [less ▲]

Prevention of Electrostatic Charge Generation in Filtration of Low-Conductivity Oils by Surface Modification of Modern Filter Media

in Tribology Transactions (2020)

The electrostatic charging behavior of filter elements operating in various hydraulic and lubricating fluids has been re-examined from the perspective of fundamental material properties of the two ... [more ▼]

The electrostatic charging behavior of filter elements operating in various hydraulic and lubricating fluids has been re-examined from the perspective of fundamental material properties of the two materials participating in the event. In contrast to the previously proposed mechanisms that focused predominantly on fluid and material conductivities, new evidence strongly suggests that the relative placement of the substrates in the triboelectric series must be taken into account. The positions occupied in the triboelectric series account for the donor/acceptor tendencies exhibited by the materials when brought close together in close proximity ( 10 nm). Nevertheless, this behavior is only an outward manifestation of the deeper underlying characteristics that include material surface energies and, looking even deeper, the associated electron work functions of the interacting materials. Herein we provide several examples of the enhanced understanding of the electrostatic charging/discharging (ESC/ESD) phenomena as they occur in the course of filtration of hydraulic and lubricating fluids through modern filter elements constructed of synthetic glass fiber and polymer materials. [less ▲]

Modelling of Passive Heat Removal Systems: A Review with Reference to the Framatome KERENA BWR Reactor: Part I

in Energies (2019)

Passive safety systems are an important feature of currently designed and constructed nuclear power plants. They operate independent of external power supply and manual interventionsand are solely driven ... [more ▼]

Passive safety systems are an important feature of currently designed and constructed nuclear power plants. They operate independent of external power supply and manual interventionsand are solely driven by thermal gradients and gravitational force. This brings up new needs forperformance and reliably assessment. This paper provides a review on fundamental approaches to model and analyze the performance of passive heat removal systems exemplified for the passive heat removal chain of the KERENA boiling water reactor concept developed by Framatome. We discuss modelling concepts for one-dimensional system codes such as ATHLET, RELAP and TRACE and furthermore for computational fluid dynamics codes. Part I deals with numerical and experimental methods for modelling of condensation inside the emergency condensers and on the containment cooling condenser while part II deals with boiling and two-phase flow instabilities. [less ▲]

LuxCube the First CubeSat Student Satellite in Luxembourg

Poster (2019, June 15)