Experimental Investigation Of A Thermally Integrated Carnot Battery Using A Reversible Heat Pump/Organic Rankine Cycle: Influence Of System Charge On Performance Of The Reversible Scroll Compressor/Expander And Global Performance

Carnot batteries are considered a promising power-heat-power storage technology for mid- and large-scale applications. Recently, the use of dual-purpose thermal machines has been proposed in Carnot batteries. In such a system, a single unit acts as heat pump (HP, compressor operation) during charging or organic Rankine cycle (ORC, expander operation) during discharging. This configuration reduces the investment cost of the technology compared to traditional Carnot batteries using two separate machines. An experimental campaign has been performed on a small-scale (1 kWel) Carnot battery pilot plant using a single scroll compressor/expander. A wide range of operational conditions has been tested in both charging and discharging mode. The influence of the system charge on the obtainable working points in both operation modes has been discussed. It has been found that lower system charges are needed to run the system in HP-mode than in ORC-mode. At these low charges, increasing the charge in HP-mode has a positive influence on the system performance at higher source and sink temperatures. At the higher charges for ORC-mode, increasing the system charge has been found to have a positive effect on the start-up of the system in the studied operation range. Next to the qualitative discussion, the system and scroll machine has been studied quantitatively

Experimental Investigation Of A Thermally Integrated Carnot Battery Using A Re y Using A Reversible Heat Pump/Or ersible Heat Pump/Organic Rankine Cy ganic Rankine Cycle: Influence Of System Char Influence Of System Charge On P ge On Performance Of The Re formance Of The Reversible ersible Scroll Compressor/Expander And Global Performance

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Oncology Section EDGE Task Force on Urogenital Cancer Outcomes: Clinical Measures of Lymphedema—A Systematic Review

Background: Valid and reliable tools to assess lymphedema are necessary to accurately evaluate status and to objectively document and measure the results of interventions. Understanding the advantages and disadvantages of each measure can inform the clinician\u27s choice of the appropriate tool to be used in the clinic or research setting. Purpose: To identify reliable and valid measurement techniques that are sensitive to change for assessing edema volume or soft tissue change in the lower extremities or genital region of patients with lymphedema. Methods: A systematic review of the literature was conducted to assess the published psychometric properties and clinical feasibility of each method identified. Task Force members independently reviewed each measure using the Cancer EDGE Rating Form. Results: Both water displacement and circumferential measurement methods by tape measure were rated as Highly Recommended to quantify lower-extremity limb volume. Water displacement was determined to be the criterion standard by which all other assessments of volume are benchmarked. Both optoelectric volumetry and bioelectric impedance analysis were rated as Recommended, and ultrasound was rated Not Recommended. Conclusion: The Urogenital Cancer EDGE Task Force highly recommends water displacement and circumferential tape measurement for use as reliable methods for assessment and documentation of change of limb volume in this patient population. Early detection of subclinical lower-extremity lymphedema in this patient population remains challenging, as there is no “index” limb that can be proven to be uninvolved in a patient population with documented pelvic node dissection/irradiation. No articles were found to support valid and reliable genital lymphedema volume measurement

Mining Train Delays

Abstract. The Belgian railway network has a high traffic density with Brussels as its gravity center. The star-shape of the network implies heavily loaded bifurcations in which knock-on delays are likely to occur. Knock-on delays should be minimized to improve the total punctuality in the network. Based on experience, the most critical junctions in the traffic flow are known, but others might be hidden. To reveal the hidden patterns of trains passing delays to each other, we study, adapt and apply the state-of-the-art techniques for mining frequent episodes to this specific problem.

Assessing the influence of compressor inertia on the delivery of grid balancing services with vapor compression heat pumps in Pumped Thermal Energy Storage

The share of intermittent renewable energy sources in power generation is ever increasing. Large scale energy storage systems provide essential grid services to ensure secure and stable energy supply. Pumped Thermal Energy Storage (PTES), a combination of a power-to-heat, a thermal storage and a heat-to-power system, could provide a possible solution. Rankine-based vapor compression heat pumps are considered as a suitable power-to-heat technology. At the moment however it is unclear if PTES is capable of delivering grid balancing services. To address this question, a dynamic model of a heat pump was made in Modelica and evaluated according to the prequalification criteria of grid balancing services. The results show that the heat pump qualifies for delivery of primary, secondary and tertiary grid balancing services when neglecting the mechanical inertia of the compressor. Neglecting mechanical inertia is a good approximation as typically an accurate prediction of the thermal performance is wanted. However, when assessing the suitability for grid balancing services, the electrical, rather than the thermal response time is of interest. This response is directly related to the compressor behavior and control. Therefore, this work also includes the sensitivity of the electric response time in function of the compressor inertia. As such providing novel insights and recommendations for the dynamic modelling of heat pumps in the context of the electrical grid balancing

Design of an experimental method to measure heat transfer between a single fin and a phase change material during melting

An experimental setup has been designed to study a single cylindrical fin placed in a cylindrical enclosure filled with phase change material (PCM). The heat flux to the fin is measured at the top of the fin. The temperature evolution at different fin heights is measured by thermocouples placed internally in the fin. The evolution of these temperatures has been studied for different heat fluxes. These temperatures provide insight in the contribution of the different fin heights to the total heat transfer to the PCM during different stages of the melting process. As such they can be used to assess the effectiveness of the fin over its length. Moreover, a method to determine the heat transfer from the fin to the PCM based on these temperature measurements is introduced. The concept is illustrated and the needed improvements to finalize the method are identified

Carnot battery : introduction of a high-level, application based sizing model

The use of renewable energy sources in the energy mix is ever increasing. Most of these renewable sources are intermittent in nature. Therefore, large-scale energy storage systems are considered essential to ensure the security of supply in energy systems. Flexible, economic and efficient electrical energy storage systems are thus needed to shift large quantities of energy from peak-production to peak-demand. Carnot batteries are a novel grid-scale energy storage concept that could potentially fulfil these needs. This paper aims to introduce Carnot batteries to a wider audience. The different system topologies proposed in the literature are presented, with a special emphasis on the intended system sizes and working temperatures. In the literature, load-shifting of renewable energy is often mentioned as possible application. Until now, the system sizing for this application has not been studied. A high-level model is presented which can be used for a primary sizing of a Carnot battery. The use of this model is illustrated by a study of the needed storage duration for load-shifting of solar PV- and wind production. It has been found that a significantly higher storage duration is needed for load shifting of wind production compared to solar production to reach the same service levels. It is thus important to take the specific use case into consideration during the system sizing

Introduction of a high-level, application based sizing methodology for carnot batteries

Due to the ever increasing share of renewable energy sources (RES) in the energy mix, large-scale energy storage systems are considered essential to ensure the security of supply in energy systems. In recent years, Carnot batteries have been introduced as an alternative grid-scale electrical storage system. In this storage concept, electrical energy is converted into heat, the heat is stored in a thermal storage system and finally converted back into electricity when needed. One of the main branches in the technology development is based on Rankine-cycles. The organic Rankine cycle (ORC) has potential for integration as the heat-to-power technology in this overall storage system. However, it is not clear how to size the system and assess its economic feasibility taking into account variable electricity production, demand and pricing. A sizing methodology based on a high-level generalized model of a Carnot battery is introduced to fill this gap. The methodology is explained in general and illustrated by a case study of load shifting of solar PV-panels for a non-residential university building with a high capacity of solar production