• Energy Research
• French National Research Agency (AN... close
• OA Publications Mandate: No close
• 2009 close

Concerted research of 4 research groups involving chemical synthesis, laser spectroscopy, electrochemistry, and theory will be aimed at demonstrating the suitability of new heteroleptic copper(I) complexes for solar energy conversion schemes. While the area of photochemistry is dominated by ruthenium(II) polypyridine complexes, little attention has been paid to copper(I) complexes. One particularly significant driving force of this program lies in the lower cost, higher abundance and lower toxicity of copper compared to ruthenium. New heteroleptic copper complexes will be prepared and investigated with respect to advancing two areas: (i) novel photo- and electro- active rod-like molecular arrays of the general type Donor-Sensitizer-Acceptor in view of long range photoinduced charge separation and (ii) photo-electrochemical devices based on the sensitization of p-type semiconductor (NiO). Synthesis, characterizations and theoretical research will be twinned aiming at a rational design of the complexes in view of the envisioned function. The expected results are the synthesis and the discovery of new copper(I) complexes with useful photophysical properties, which will in turn lead to new breakthroughs in the rational design of copper complexes for long-range photoinduced charge separation and for photoelectrochemical devices, where traditional ruthenium complexes are used. All this will be of fundamental importance for establishing new materials for solar energy convsersion.

In the context of global warming combined with the depletion of fossil and fissile energy resources, there is a recent but sustainable increase of interest in the development of researches focusing on high-performance buildings which actually constitutes one of the most significant energy consumers. Solar energy will belong to the energy mix of these future high performance buildings. Among promising solutions, we consider in this project, multi-functional building envelop components such as Thermal/Photovoltaic (PV-T) double skin façade that converts solar energy in electricity and heat. This double-skin façade is composed by the primary façade of the building separated from a secondary photovoltaic façade by an air gap. The photovoltaic façade is constituted by an alternation of PV cells areas which are opaque and transparent glass areas to let the light enter inside the building. Natural convection is an inexpensive and convenient way to cool the PV cells and to recover heat that could be injected in the energy mix during cold period or valorised as solar chimney for driving crossing natural ventilation within the building during hot period. This has to be grounded on fundamental experimental and numerical investigation of natural convection in channel configuration which represents the kernel of the present project. More precisely, we address the problem of the interaction of heat transfer and flow in an open vertical channel heated on its sides. The key points that are to be worked out are: 1) How the energy supplied is shared out between kinetic energy and enthalpy ? This point is closely related to thermal stratification and chimney effect 2) How is the interaction between the heat transfer and the flow at the small scales – particularly in the near-wall region? That leads to a better understanding of global behaviour of the flow including transition 3) To what extent the wall properties (surface and inner) modify the flow behaviour ? That includes radiation effects and conduction properties. In order to bring basic knowledge on these questions, three experimental apparatus are planed which will be accompanied or defined in order to feed accurate numerical approaches. Both approaches are in addition reciprocally complementary. A water flow channel that will be ready in September 2008, inhibits radiations and will be used to study convection with uniform and non-uniform heating. An air channel that is actually operational, allows for an accurate measurement of convective heat flux with uniform and non-uniform heating. The third experiment that is to be built is an air flow channel heated with a sunshine simulator. It is designed to allow an easy replacement of the channel wall in order to change wall properties. The global aim of this proposal is to understand the physical mechanisms that drive heat transfer in vertical channels including the effects of wall properties (inner and surface thermal properties) and non uniform heating sources distribution. The first task is dedicated to the study of convection only. The main work is to describe and understand heat transfer in the near-wall region and to reach a meaningful global model for uniform heat distribution in one wall. The second part of this first task consist in analysing effect of non-uniform heating distribution on heat transfer and flow development. Objective will be to find relevant parameters to describe heat transfer in this configuration. The second task will focus on the coupling of convection and wall thermal properties i.e. radiation heat transfer for wall surface properties and conduction for wall inner thermal properties (related to the primary building envelop constitution). Indeed, in real solar energy integrated systems (BIPV), the lighted wall (secondary skin) can be an assembly of photovoltaic cells and glass and the other plate is the wall of the building. Therefore, a wide range of materials can be encounter and the classical heat flux boundary condition no longer holds. That is why we choose to include the walls in the system under study. The first work of the second task is dedicated to influence of inner properties of the wall which led to conduction coupling. The second part concerns the influence of surface wall properties which led to radiation coupling. This experimental study will be led under simplified hypothesis (uniform heating and diffuse-grey materials). However effects of a non-uniform heating and the effects of nondiffuse and nongrey surfaces will be investigated. Due to the difficulty to make an experimental study with this complex radiative properties, this point will be work out numerically. These results might induce further experimental investigations.