| 25431. |
- Monfared, Behzad, 1983-
(författare)
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Simulation of solid-state magnetocaloric refrigeration systems with Peltier elements as thermal diodes
- 2017
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Ingår i: International journal of refrigeration. - : Elsevier. - 0140-7007 .- 1879-2081. ; :74, s. 322-330
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic refrigeration as an alternative for vapor-compression technology has been the subject of many recent studies. Most of the studies focus on systems with limited cycle frequency in which a fluid transfers heat to and from the magnetocaloric material. A suggested solution for increasing the frequency is use of solid-state magnetic refrigeration in which thermal diodes guide the heat from the cold end to the warm end. In this work a solid-state refrigeration system with Peltier elements as thermal diodes is modeled in details unprecedented. The performance of Peltier elements and magnetocaloric materials under their transient working conditions after reaching cyclic steady state are simulated by two separate computer models using finite element method and finite volume method. The models, in parts and as a whole, are verified. The verified finite element model is used for a parametric study and the results are analyzed.
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| 25432. |
- Monfared, Behzad, 1983-, et al.
(författare)
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Small Ammonia Heat Pump with Variable Speed Compressor
- 2012
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Konferensbidrag (refereegranskat)abstract
- Ammonia is a natural refrigerant which has been used continuously for more than 100 years. From almost any technical perspective, it is an attractive refrigerant, having good cycle efficiency, good heat transfer properties and low pressure drop compared to most other refrigerants. The volumetric refrigerating effect is also higher than for other fluids of the same vapor pressure. Applications are nowadays restricted almost exclusively to large industrial or commercial systems.We have previously demonstrated that ammonia is also a viable refrigerant for small systems (Palm 2008, Monfared and Palm 2011). In this paper we report on additional tests with a small capacity (7.2 kW) water to water heat pump for sanitary hot water production and space heating. Particularly, the losses in the compressor, electric motor and variable speed drive are investigated under full and part load conditions. New data for the general performance of the heat pump in terms of heat delivered at 60 °C for sanitary hot water production and at 40 °C for space heating, energy efficiency, etc. will also be reported.
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| 25433. |
- Monghasemi, Nima, et al.
(författare)
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Rank-Based Assessment of Grid-Connected Rooftop Solar Panel Deployments Considering Scenarios for a Postponed Installation
- 2023
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 16:21
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Tidskriftsartikel (refereegranskat)abstract
- Installing solar photovoltaic panels on building rooftops can help property managers generate renewable energy and reduce electricity costs. However, the existence of multiple efficiency indicators and ambiguity in interpreting these metrics limits the comparison of the performance of individual installation projects. This paper presents a methodology using data envelopment analysis to evaluate suitable candidates for rooftop solar panel installation. This approach integrates rooftop area, solar irradiation, temperature, costs, energy yield, and revenue to evaluate the relative efficiency of each building. To demonstrate the methodology, it was applied to rank 22 residential buildings, revealing the top performers for installation in 2022. The approach was subsequently adapted to assess potential outcomes under deferred implementation up to 2030, encompassing a diverse range of climate and pricing scenarios. Five installations were found to be optimal irrespective of the future scenarios. In addition, a super-efficiency approach was applied to overcome the low level of discrimination among the possible installations and to rank each individual unit uniquely. The analysis is designed to guide property owners in identifying favorable solar photovoltaic investments within their portfolios under changing conditions.
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| 25434. |
- Monie, Svante, 1972-, et al.
(författare)
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Electricity balancing capacity, emissions, and cost comparison of three storage-based local energy systems for variable power generation
- 2019
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Ingår i: 9th International Workshop on Integration of Solar Power and Storage into Power Systems.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This study compares three energy system setups for supplying the electricity and heat demand in a residential area. Two of the setups contain district heating and a combined heat and power unit. The first setup contains a thermal storage and the second contains an electric battery. The third setup is all electric (incl. the heat production). The second setup reduced the electricity balancing demand the most, but had the highest CO2,eq-emissions. The third setup had no emissions, but the highest cost. This setup also increased the balancing demand. The first system, with the thermal storage, performed most satisfying when electricity balancing capacity, CO2,eq-emissions, and costs were weighed together.
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| 25435. |
- Monie, Svante, 1972-, et al.
(författare)
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Power-to-heat on the reserve capacity market-Policy implications considering economic constraints and competing heat production
- 2022
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Ingår i: Journal of Renewable and Sustainable Energy. - : AIP Publishing. - 1941-7012. ; 14:5
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Tidskriftsartikel (refereegranskat)abstract
- Studies have shown that surplus power from variable renewable electricity generation can be consumed in electric boilers or compressor heat pumps, i.e., Power-to-Heat (P2H), for heat production. This potentially provides power balancing for the electric grid and can also decarbonize and/or reduce biofuel demand in the district heating (DH) sector. This sector-coupling of thermal and electrical systems is, how-ever, limited by production planning complexity, grid fees, tariffs, and risk-averse actors. The conditions for P2H production vary between DH-systems due to non-homogeneity in the configuration of production units in different systems. This study investigates the economic feasibility of placing bids for P2H electricity consumption on the reserve capacity market in three different DH systems. It is assumed that P2H electricity consumption is controlled by a hypothetical balance operator. To increase production flexibility, the DH systems are equipped with heat storage where P2H-produced heat is stored. The results show that P2H on the reserve capacity market can increase revenue for DH operators, but DH systems with co-generation of heat and electricity risk reducing income from power production. Furthermore, stored heat needs to compete with cost-efficient base-load production to avoid the large storage required. The power balancing potential of P2H in DH systems is generally limited by the installed P2H capacity as well as the rest of the constituents and the production strategy of the DH system. To overcome these limitations, policies are needed that reward power balancing services and provide investment support for P2H capacity and heat storage. Published under an exclusive license by AIP Publishing.
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| 25436. |
- Monie, Svante W., 1972-, et al.
(författare)
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Potential to balance load variability, induced by renewable power, using rock cavern thermal energy storage, heat pumps, and combined heat and power in Sweden
- 2023
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 343
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Tidskriftsartikel (refereegranskat)abstract
- Large shares of variable renewable electricity (VRE) generation increase the demand for flexible power balancing capacities for handling power surpluses and deficits. Within district heating (DH) production systems, electricity can be produced in combined heat and power (CHP) plants but also consumed in heat pumps, and thus contribute with balancing capacity. However, this power balancing potential in DH production units is limited by heat load variations. To improve the potential, large-scale thermal energy storage (TES) can be used to increase heat-load flexibility. This study investigates the power balancing capacity of 85 existing Swedish DH systems, with hypothetical access to rock cavern oil depots assumed to have been converted into TES units. In the study, the Swedish power load is assumed to be covered by 60 % wind and 10 % solar power. The results show that Swedish DH systems, on a national scale, could reduce power deficits and surpluses by approximately 9 % respectively. There will be competition between heat pumps and CHP units for DH load supply while providing power balancing services. The use of heat pumps could also, on national level, yield a reduced fuel use in DH production by about 10 % when compared to conventional DH system operation. The study highlights the impact the temporal distribution and annual shares of VRE surpluses and deficits have on the fuel use.
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| 25437. |
- Monika, K., et al.
(författare)
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Theft vehicle scheme using cloud computing techniques
- 2017
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Ingår i: Journal of Advanced Research in Dynamical and Control Systems. - : Institute of Advanced Scientific Research, Inc.. - 1943-023X. ; 9:Special Issue 2, s. 1023-1031
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Tidskriftsartikel (refereegranskat)abstract
- Due to proliferation in the metropolitan areas there existing problem of poor traffic congestion has grown at alarming event and it is not easy to find the stolen vehicles. So here we use Theft vehicle detection system for finding the theft vehicles using open source hardware of RASPBERRY PI.This system make use of RFID and embedded technology. Here each vehicle is placed with RFID tag. Whenever the RFID reader reads the RFID tag in the stolen vehicle it alert the traffic police and the signal will be automatically changed into red light until the vehicle is recovered from the stolen person. This is achieved by connecting cloud technology with server which is handle by the traffic police. When the traffic controller ensures that the particular vehicle is missed then, whenever that particular vehicle crossed by the any signal red light blinks automatically then cloud displays the message with vehicle number.By using this system, we can alert the signal and can easily find the stolen vehicle by tracking the RFID tag.
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| 25438. |
- Monsel, Juliette, 1994, et al.
(författare)
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Geometric energy transport and refrigeration with driven quantum dots
- 2022
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 106:3
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Tidskriftsartikel (refereegranskat)abstract
- We study geometric energy transport in a slowly driven single-level quantum dot weakly coupled to electronic contacts and with strong on-site interaction, which can be either repulsive or attractive. Exploiting a recently discovered fermionic duality for the evolution operator of the master equation, we provide compact and insightful analytic expressions of energy pumping curvatures for any pair of driving parameters. This enables us to systematically identify and explain the pumping mechanisms for different driving schemes, thereby also comparing energy and charge pumping. We determine the concrete impact of many-body interactions and show how particle-hole symmetry and fermionic duality manifest, both individually and in combination, as system-parameter symmetries of the energy pumping curvatures. Building on this transport analysis, we study the driven dot acting as a heat pump or refrigerator, where we find that the sign of the on-site interaction plays a crucial role in the performance of these thermal machines.
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| 25439. |
- Monsel, Juliette, 1994, et al.
(författare)
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Non-geometric pumping effects on the performance of interacting quantum-dot heat engines
- 2023
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Ingår i: European Physical Journal: Special Topics. - 1951-6401 .- 1951-6355. ; 232:20-22, s. 3267-3272
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Tidskriftsartikel (refereegranskat)abstract
- Periodically driven quantum dots can act as counterparts of cyclic thermal machines at the nanoscale. In the slow-driving regime of geometric pumping, such machines have been shown to operate in analogy to a Carnot cycle. For larger driving frequencies, which are required to increase the cooling power, the efficiency of the operation decreases. Up to which frequency a close-to-optimal performance is still possible depends on the magnitude and sign of on-site electron–electron interaction. Extending our previous detailed study on cyclic quantum-dot refrigerators [Phys. Rev. B 106, 035405 (2022)], we here find that the optimal cooling power remains constant up to weak interaction strength compared to the cold-bath temperature. By contrast, the work cost depends on the interaction via the dot’s charge relaxation rate, as the latter sets the typical driving frequency for the onset of non-geometric pumping contributions.
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| 25440. |
- Montero, Kerry, et al.
(författare)
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Key elements in the development and delivery of a community based multi stakeholder approach to road safety education for young adult road users
- 2016
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Konferensbidrag (refereegranskat)abstract
- This paper builds upon research presented at the RS4C Conference in 2013 which described the design and development of the F2D community road safety intervention strategy in the State of Victoria, Australia. F2D is a program using trained university undergraduates as road safety education facilitators and ambassadors to empower young people to be safer road users. Ongoing government and public concerns about young driver overrepresentation in casualty crashes in Victoria has resulted in specific legislation and education interventions. The integrated Fit to Drive (F2D) model of research, development, delivery and evaluation involves a multi stakeholder approach to road safety education for young adult road users that is local and long term. The half day F2D workshop program for 16 year olds currently involves over 58 Local Government Areas, 220 Government, Independent and Catholic schools, 26,000 young people and has trained more than 500 university undergraduates to be road safety facilitators. F2D is part of the Government of Victoria’s Road Safety Strategy and is supported by major stakeholders in road safety education - Transport Accident Commission (TAC), Victoria Police, VicRoads, Department of Education and Training (DET), Metropolitan Fire Brigade (MFB), Country Fire Authority (CFA), State Emergency Services (SES), Royal Auto Club of Victoria (RACV).The program has been made available to all schools, extending the collaborative ability and potential of “F2D community networks” (local senior school groups, Technical and Further Education (TAFE), local government, universities) to address road trauma in this vulnerable population group. The F2D undergraduate peer led approach, combined with targeted community partnerships presents as a local community road safety response and community capacity building model. F2D offers a potential paradigm for other communities, within the context of the “Decade of Action for Road Safety”. Drawing on fifteen years’ experience of developing and sustaining community partnerships to deliver road safety education in schools, this paper describes and analyses the key elements of successful community partnerships in the prevention of road trauma.
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