Limiting the Nitrogen Losses by N-tax and Bioenergy Support: A Quantitative Analysis of Environmental Policy Mix Impacts in the North of France

This paper is devoted to assessment of policy mix impacts regarding nitrogen pollutants. The analysed policy combines a tax on the nitrogen input and incentives promoting perennial crops assumed to be low input ones. We show that perennial crop subsidy increases significantly the tax efficiency, compatible with the balanced budget of the Regulatory Agency in charge of the environment. Based on a MILP agricultural supply model, quantitative analysis provides assessment of impacts regarding land use, farmers income, and N losses at the North France level.Bio-economic model, mathematical linear programming, environmental policy mix, N-fertilizer tax, bio-energy support, Environmental Economics and Policy,

Modeling of the THS-II series/parallel power train and its energy management system

Full text available at http://www.fisita2010.com/programme/programme/pdf/F2010B107.pdfInternational audienceThe hybridization of the conventional thermal vehicles nowadays constitutes a paramount importance for car manufacturers, facing the challenge of minimizing the consumption of the road transport. Although hybrid power train technologies did not converge towards a single solution, series/parallel power trains with a power-split electromechanical transmission prove to be the most promising hybrid technology. In fact, these power trains show maximum power train overall efficiency and maximum fuel reduction in almost all driving conditions compared to the conventional and other hybrid power trains

R-1234yf Mixtures for replacing R-407C in residential heat pumps

International audienceThis paper deals with the design of air-to-water heat pumps dedicated to the replacement of old oil boilers. Based on the future building regulation to be issued in France in 2012 for old building refurbishment, the allocation for heating, cooling, lighting, ventilation, and hot water will be of 80 kWh/m2.yr. One of the concerns of the current heat pump technology using either R-407C or R-410A is the high global warming potential of those refrigerant blends. The research project presented in this paper aims at defining new refrigerant blends capable to replace R-407C in those air-to-water heat pumps. The refrigerant blends, which have been modeled and tested, have GWPs varying between 200 and 600 kg CO2 kg-1. Several refrigerants have been simulated using REFPROP 8. One has been selected and tested on an air-to-water heat pump developed at the laboratory. Energy performances of this blend are similar to those of R-407C

Analysis and developpment of a Turbivo compressor for MRV applications

The mechanical vapor recompression is an efficient process to decrease energy consumption of drying processes. In order to use the mechanical vapor recompression (MVR) in residential clothe dryers, the volumetric Turbivo technology is used to design a dry water vapor compressor. The Turbivo volumetric machine is composed mainly of a rotor with one blade, a stator, and a mobile oscillating thrust. The advantages of Turbivo(R) technology are the absence of contact between rotor and stator as well as the oil-free operation. A model of the Turbivo compressor, including kinematic, dynamic, and thermodynamic analysis is presented. The compressor internal tightness is ensured by a surface treatment of the compressor components. Using the model, a water vapor Turbivo compressor of 12m3/h and compression ratio of 5 has been sized and realized. The compressor prototype will be tested on a dedicated test bench to characterize its volumetric and isentropic efficiencies

Heat Pump With a Condenser Including Solid-Liquid Phase Change Material

The growing usage of heat pumps increases the global electricity demand. During winter, the external temperature peak is at noon whereas electricity peak is at the end of the afternoon. Latent heat storage can be used to benefit from the time lag between these two periods. In this application phase change material (PCM) is integrated in the condenser of an air-to-air heat pump. The condensing temperature is used to melt down the PCM at noon. Then, during electricity peak load, the compressor is turned off and the indoor air of the house can be heated by exchanging heat with the melted PCM through the condenser. The condenser design is important to fulfill heating requirements since PCMs have in general low thermal conductivity. A dynamic model using Dymola is applied to size and simulate a prototype. Results show that a well sized heat exchanger can fulfill any heating requirements, however it is voluminous compared to an equal capacity regular condenser

What Does it Take to be a Social Agent?

The aim of this paper is to present a philosophically inspired list of minimal requirements for social agency that may serve as a guideline for social robotics. Such a list does not aim at detailing the cognitive processes behind sociality but at providing an implementation-free characterization of the capacities and skills associated with sociality. We employ the notion of intentional stance as a methodological ground to study intentional agency and extend it into a social stance that takes into account social features of behavior. We discuss the basic requirements of sociality and different ways to understand them, and suggest some potential benefits of understanding them in an instrumentalist way in the context of social robotics.The aim of this paper is to present a philosophically inspired list of minimal requirements for social agency that may serve as a guideline for social robotics. Such a list does not aim at detailing the cognitive processes behind sociality but at providing an implementation-free characterization of the capacities and skills associated with sociality. We employ the notion of intentional stance as a methodological ground to study intentional agency and extend it into a social stance that takes into account social features of behavior. We discuss the basic requirements of sociality and different ways to understand them, and suggest some potential benefits of understanding them in an instrumentalist way in the context of social robotics.Peer reviewe

Heat Pump Driven by a Gas Engine for Heating and Domestic Hot Water Generation

Air source heat pumps driven by a gas engine is a known technology. In this paper, we describe a Heat Pump driven by a gas engine that uses grey waters as the cold source producing domestic hot water and heat for the hydronic system. Grey waters are coming exclusively from kitchen’s and bathrooms’ waste water and their average temperature is about 30°C. This temperature is constant all along the year. The recovered lukewarm water is stored at atmospheric pressure in a tank. The domestic hot water and the heating water are produced instantaneously by the heat pump and stored in a tank, and hot water is delivered at 58 °C. The paper presents the architecture resulting from a heat integration and exergy analysis study. It allows the heat recovery from the grey waters for the generation of domestic hot water while heat recovery from the engine is used for heating the building. A sensitivity analysis is performed on the ratio between the heat recovered from the grey waters and the heat recovered from the engine when the thermal efficiency of the engine varies. Simulations show also how to handle the engine operation during the heating period and in summer conditions for the climatic conditions of Paris. The seasonal energy efficiency of the system is calculated based on simulations; they predict a seasonal energy efficiency of 2 for generating hot water at 58 °C

Design Of A Turgo Two-Phase Turbine Runner

A two-phase impulse turbine used to replace the classic expansion valve in a refrigeration system needs a nozzle/expander to transform the flow stored enthalpy into kinetic energy, and a runner that comes afterwards to transform the flow kinetic energy into torque. That process transforms the isenthalpic expansion of the refrigerant into, ideally, an isentropic one. Replacing a classic isenthalpic expansion with a nearly isentropic one increases the cycle cooling capacity by 8% up to 20 % for the same compressor input power and generates an additional electric power by the two-phase turbine. During the expansion in the nozzle, the static pressure of the flow decreases and a phase change occurs, for the flow is slightly subcooled, by 2 to 3 K, at the nozzle entrance. A Turgo turbine runner design is presented. The runner makes use of the kinetic energy of a two-phase flow and transforms it into torque. The geometry and material of the runner components are chosen to provide mechanical integrity and high efficiency. The design takes into consideration the number of buckets, the flow behavior inside a bucket, the power loss due to drag force, the flow impingement angle with the bucket and many other factors. The variation of the efficiency of the runner with the refrigerant quality and the gas physical properties is also studied. FEM (finite element method) is used to calculate the mechanical stress on the structure of the runner that is supposed to withstand static and fatigue stress, and erosion due to the two-phase nature of the flow. FEM is also used to visualize the flow inside the bucket and to estimate the power loss due to drag force. The calculated efficiency of the runner is then compared to the efficiency of a similar tested runner

Energy efficient air to air heat pump operating with R-1234yf

International audienceSignificant improvements in energy performance of air-to-air heat pumps are the major reason of their introduction in the late '90s for heating buildings in Japan and several European countries. They are installed in multi-dwelling units and in individual houses. Some of them are using variable speed compressors. European existing air-to-air heat pumps are not adapted for the low-energy building requirements. Their heating capacity is relatively higher than the heating demand and their energy efficiency is not sufficient. This paper presents a low-capacity heating system: a mini-heat pump (MHP). The MHP consists of mini-channel heat exchangers for the condenser and evaporator. In order to improve the overall energy efficiency, a recovery air-to-air heat exchanger (RHX) fulfills a significant part of a passive house heating demand. A first prototype of the MHP is realized and series of tests are presented in this paper with two refrigerants: R-134a and R-1234yf