A Simplified Model For Assessing Improvement Potential Of Air-To-Air Conditioners And Heat Pumps

Many countries have adopted energy efficiency regulations for mini-split type air conditioners in the world. For these products, energy efficiency metrics is moving to seasonal performance evaluation. Many countries have already changed their metrics and many others are planning to customize the ISO 16358:2013 CSPF (Cooling Seasonal Performance Factor) and HSPF (Heating Seasonal Performance Factor) indicators to their own climate and use of air conditioners. To build policies to justify the need for implementing MEPS (Minimum Energy Performance Standard) and energy label programs, technico-economic model is required. A standard product is to be modeled as well as potential improvement options. The complexity of the task increases significantly when shifting from one or two test point (rated EER or COP) to several test points to compute SEER and SCOP. In this context, we propose a simple model to evaluate the various EER and COP values for different part load conditions in such a regulatory context. The model is first described; governing equations by component are given, as well as technical parameters required as input. The model is validated using several different units for which EER and COP at part load conditions according EU seasonal performance EN14825 are known. Potential of the model to simulate improvement options in view of regulatory development is discussed in conclusion, as well as potential improvements

Energy Consequences of Non-optimal Heat Pump Parameterization

The substitution of low-performance gas and fuel boilers by air to water electrical heat pumps is a solution to meet the energy challenge to reduce GHG dwellings emissions. Indeed, most dwelling emissions in Europe are due to heating and DHW generation with fossil fuels. Apart from low carbon emissions, high energy savings are expected from rated performances, but an AWHP may not deliver the expected efficiency because of a bad commissioning. Nowadays, these machines present a high number of parameters – over 40 on average – to be set during the installation, which makes this process very complex. Unfortunately, the parameter setting is a crucial step for the proper operation of the system throughout its life cycle. A non-optimal choice of AWHP parameters may lead to severe performance losses or discomfort. The first part of the paper describes the functions and parameters that the installer must adjust for the commissioning phase. In a second step, the consequences of a non-optimal parameterization of an AWHP are evaluated. This analysis is based on a computer model using Modelica language. The model consists of a heating system, installed in a typical detached dwelling. Simulations are run by pairing the heat pump with the dwelling and the heating system. Simulations show the potential energy savings and the accuracy of indoor air control when control parameters, in particular the heating curve, are adapted to the dwelling and to the heating network. Final results confirm that an optimization of the parameterization of an AWHP makes a significant difference, in both energy savings and indoor air temperature control accuracy

Non-Intrusive Performance Assessment Method For Heat Pumps: Experimental Validation And Robustness Evaluation Facing Faults

Thanks to their high theoretical efficiency, residential heat pumps (HP) are a promising technology when attempting to reduce the energy consumption of heating in dwellings. Evaluation of their real performances on-field is thus crucial to promote their development and deployment. However, measuring accurately real heating capacity of air-to-air HP is not easy, since measuring air enthalpy and mass flow rate is challenging. A previously developed non-intrusive internal method based on the compressor energy balance has been improved. It can calculate the coefficient of performance (COP) of different HP types, including air-to-air, on field, thanks to real-time measurements, without interfering with normal operation of the system, and without technical data of the specific heat pump. In this study, a complete validation of this method has been led on a test bench, using an air-to-water HP in order to compare the results of the method with the water-side measurements. This internal refrigerant method was tested for various climatic conditions and heating needs, in stationary and dynamic conditions, including starting and defrosting phases. Different faults were simulated to analyse the behaviour of the method in these conditions, including refrigerant undercharging and exchanger fouling. The analysis also extends to identifying which parameters need to be observed to early detect these faults. The method proves to be robust and its uncertainty to remain low, although it varies with the different working phases. The precise knowledge of real-time performances obtained with this method can help to assess the performance impact of faults and thus to improve associated fault detection and diagnostic methods. On a longer-term scale, the comparison of measured field performances and performances obtained via simplified models, such as regulatory models for instance, could give interesting indications to improve these models

Integral and Differential Model of Hermetical Compressor Heat Losses Including Experimental Validation

The current evaluation of heating and cooling system performances has become a major issue in European buildings sector. A promising method for measuring heat pump performances on-field has been previously developed and published. However, the accuracy of the method is strongly dependent on the evaluation of heat transfer from compressor towards the ambient air. In this paper a developed compressor heat transfer model that couples integral and differential formulations is presented. The model consists of three fundamental steps: thermodynamic analysis of the compression process, detailed thermophysical flow analysis using a CFD software, and finally compressor thermal network analysis consisting of integral equations that describe heat transfer of solid-fluid interfaces. Temperature distribution of the compressor shell is the main output of the model. Internal and external thermal profiles obtained from the numerical model and experimental measurements are compared in one operating condition at two compressor speeds. The RMS errors of external profiles are 3.20 °C and 1.96 °C, at 30 rps and 60 rps, respectively. The model can be used to determine the minimum number of surface temperature sensors and their locations on the compressor shell necessary to measure heat losses on-field. More accurate evaluation of compressor heat losses towards the ambient air will improve the accuracy of the performance measurement method

Deux nouveaux documents linguistiques en ancien occitan rouergat (1441, 1467)

1. Nous avons édité, voici plus de vingt ans (Olivier/Rivière, 1994), deux documents en occitan médiéval découverts dans le fonds Deribier (Archives départementales du Cantal, cote 125 J 47), documents que nous avions supposé provenir de Haute-Auvergne, comme la plupart des documents contenus dans ce fonds. Le premier document est une lettre écrite à Paris un 4 octobre contenant une demande d’argent d’un neveu qui signe Lopiac à son oncle qui n’est pas nommé. Au dos de cette lettre figure un ..

Infrared study of transitional disks in Ophiuchus with Herschel

Context. Observations of nearby star-forming regions with the Herschel Space Observatory complement our view of the protoplanetary disks in Ophiuchus with information about the outer disks. Aims. The main goal of this project is to provide new far-infrared fluxes for the known disks in the core region of Ophiuchus and to identify potential transitional disks using data from Herschel. Methods. We obtained PACS and SPIRE photometry of previously spectroscopically confirmed young stellar objects (YSO) in the region and analysed their spectral energy distributions. Results. From an initial sample of 261 objects with spectral types in Ophiuchus, we detect 49 disks in at least one Herschel band. We provide new far-infrared fluxes for these objects. One of them is clearly a new transitional disk candidate. Conclusions. The data from Herschel Space Observatory provides fluxes that complement previous infrared data and that we use to identify a new transitional disk candidate.Comment: 21 pages, with 5 figures. Accepted in Astronomy & Astrophysic

DECK: A new model for a distributed executive kernel integrating communication and multithreading for support of distributed object oriented application with fault tolerance support

DECK (Distributed Executive Communication Kernel) is a communication layer that provides support for multithreading and fault tolerance support. The approach retained in DECK is close to other distributed communication kernels like PM2, Athapascan, Nexus, TPVM or Chant in its way to integrate communication and multithreading to efficiently overlap communication by computation and provide low latency remote thread creation mechanisms. However, DECK differs from these communication kernels from the services offered and its modular architecture. The main goal of DECK is to implement a new model for the design of distributed executive kernel to efficiently use the new underlying hardware architectures (SMP architectures and fast communication adapters like Myrinet or memory oriented adapter like SCI) and provide a portable layer that abstract the problems linked with the integration of communication and multithreading while offering support for heterogeneity. A great lack in the current implementation of communication libraries or distributed executive kernel is the support for basic services at the thread level and support for fault tolerance support. Indeed, communication library like PVM or MPI are often used as communication layer to ensure portability and take benefits of specific implementation to ensure a good efficiency on specific architectures however the support for fault tolerance support, multithreading, scalability and interoperability are usually not offered. In the case of DECK, we propose a model where a distributed application can dynamically instantiate clusters of processes among an heterogeneous network of computers or parallel machines and this using multiple communication protocols or communication interfaces to ensure good performances regarding the underlying hardware architecture. The programming model proposed offer both classic synchronous and asynchronous remote service calls for thread creation and message passing for synchronization and data exchange. These basic functionalities, that form the low level communication and execution layer of DECK, are enforced by a service layer that propose the basic fault tolerant services like naming and group services or data management services for the marshaling and un-marshalling of complex data structures. The layered and modular approach followed by DECK enable many other extensions while keeping a high degree of portability and efficiency.Sistemas Distribuidos - Redes ConcurrenciaRed de Universidades con Carreras en Informática (RedUNCI

Fatal Events in Cancer Patients Receiving Anticoagulant Therapy for Venous Thromboembolism.

In cancer patients treated for venous thromboembolism (VTE), including deep-vein thrombosis (DVT) and pulmonary embolism (PE), analyzing mortality associated with recurrent VTE or major bleeding is needed to determine the optimal duration of anticoagulation.This was a cohort study using the Registro Informatizado de Enfermedad TromboEmbólica (RIETE) Registry database to compare rates of fatal recurrent PE and fatal bleeding in cancer patients receiving anticoagulation for VTE.As of January 2013, 44,794 patients were enrolled in RIETE, of whom 7911 (18%) had active cancer. During the course of anticoagulant therapy (mean, 181 ± 210 days), 178 cancer patients (4.3%) developed recurrent PE (5.5 per 100 patient-years; 95% CI: 4.8-6.4), 194 (4.7%) had recurrent DVT (6.2 per 100 patient-years; 95% confidence interval [CI]: 5.3-7.1), and 367 (8.9%) bled (11.3 per 100 patient-years; 95% CI: 10.2-12.5). Of 4125 patients initially presenting with PE, 43 (1.0%) died of recurrent PE and 45 (1.1%) of bleeding; of 3786 patients with DVT, 19 (0.5%) died of PE, and 55 (1.3%) of bleeding. During the first 3 months of anticoagulation, there were 59 (1.4%) fatal PE recurrences and 77 (1.9%) fatal bleeds. Beyond the third month, there were 3 fatal PE recurrences and 23 fatal bleeds.In RIETE cancer patients, the rate of fatal recurrent PE or fatal bleeding was much higher within the first 3 months of anticoagulation therapy