scholarly journals Change of Heating and Cooling Degree-Hours for Different Base Temperatures: A Case Study of Bandırma

Author(s):  
Asiye ASLAN
Keyword(s):  
Author(s):  
A. Paulsen ◽  
H. Dumlu ◽  
D. Piorunek ◽  
D. Langenkämper ◽  
J. Frenzel ◽  
...  

AbstractTi75Ta25 high-temperature shape memory alloys exhibit a number of features which make it difficult to use them as spring actuators. These include the high melting point of Ta (close to 3000 °C), the affinity of Ti to oxygen which leads to the formation of brittle α-case layers and the tendency to precipitate the ω-phase, which suppresses the martensitic transformation. The present work represents a case study which shows how one can overcome these issues and manufacture high quality Ti75Ta25 tensile spring actuators. The work focusses on processing (arc melting, arc welding, wire drawing, surface treatments and actuator spring geometry setting) and on cyclic actuator testing. It is shown how one can minimize the detrimental effect of ω-phase formation and ensure stable high-temperature actuation by fast heating and cooling and by intermediate rejuvenation anneals. The results are discussed on the basis of fundamental Ti–Ta metallurgy and in the light of Ni–Ti spring actuator performance.


2018 ◽  
Vol 385 ◽  
pp. 449-454 ◽  
Author(s):  
Artem Alimov ◽  
Dmitry Zabelyan ◽  
Igor Burlakov ◽  
Igor Korotkov ◽  
Yuri Gladkov

Finite element method is the most powerful tool for development and optimization of the metal forming processes. Analysis of titanium alloy critical parts should include the prediction of microstructure since their mechanical and technological properties essentially depend on the type and parameters of the microstructure. The technological process of parts production for aerospace applications is multi-operational and consists of deformation, heating and cooling stages. Therefore, it is necessary to simulate the microstructure evolution to obtain high quality parts. In presented paper FE simulation coupled with microstructure evolution during hot forging of TC11 titanium alloy has been performed by QForm FEM code. Constitutive relationships, friction conditions and microstructure evolution model have been established using the experiments. The kinetics of phase transformations has been described by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) phenomenological model. The approach is illustrated by industrial case study that proved its practical applicability and economic advantages for technology development of titanium alloy critical parts.


2021 ◽  
Author(s):  
Taha Sezer ◽  
Abubakar Kawuwa Sani ◽  
Rao Martand Singh ◽  
David P. Boon

<p>Groundwater heat pumps (GWHP) are an environmentally friendly and highly efficient low carbon heating technology that can benefit from low-temperature groundwater sources lying in the shallow depths to provide heating and cooling to buildings. However, the utilisation of groundwater for heating and cooling, especially in large scale (district level), can create a thermal plume around injection wells. If a plume reaches the production well this may result in a decrease in the system performance or even failure in the long-term operation. This research aims to investigate the impact of GWHP usage in district-level heating by using a numerical approach and considering a GWHP system being constructed in Colchester, UK as a case study, which will be the largest GWHP system in the UK. Transient 3D simulations have been performed pre-construction to investigate the long-term effect of injecting water at 5°C, into a chalk bedrock aquifer. Modelling suggests a thermal plume develops but does not reach the production wells after 10 years of operation. The model result can be attributed to the low hydraulic gradient, assumed lack of interconnecting fractures, and large (>500m) spacing between the production and injection wells. Model validation may be possible after a period operational monitoring.</p>


2017 ◽  
Vol 12 (3) ◽  
pp. 54-68 ◽  
Author(s):  
Fehmi Görkem Üçtuğ ◽  
Vedat Can Baltalı

This study has been undertaken to develop a consumer-oriented feasibility method for a hybrid photovoltaic (PV)-battery energy storage (BES) system by analyzing a real life house in Istanbul, Turkey, as a case study. The hourly electricity demand of the house was estimated by carrying out a detailed survey of the life style and daily habits of the household. No algorithm of any kind was used for the estimation of the energy demand with the exception of relating the lighting requirement to the daylight hours and the heating and cooling requirements to the seasonal weather changes. The developed method estimates the annual demand with an overall error of 8.68%. The net grid dependency and the feasibility of the PV-BES system was calculated for different combinations of PV and BES system sizes. It was found that when the maximum available roof area is used for PV installation and when the BES system size is increased, it is possible to achieve almost zero net grid dependency, and it is estimated that houses that are in regions with more abundant solar radiation and/or with lower annual electricity consumption, can reach zero net grid dependency. However, the feasibility indicator, which is the payback period, turned out to be no less than 25 years in any of the scenarios. The reasons for the infeasibility are the high prices of PV and BES systems as well as the current restriction in the regulations in Turkey, which prevents BES system owners from participating in unlicensed energy generation schemes and selling excess electricity back to the grid. In order to overcome this situation, regulations should be updated to allow BES system owners to benefit from feed-in-tariff schemes, thereby increasing the popularity of both PV and BES usage in Turkey.


Energies ◽  
2017 ◽  
Vol 10 (10) ◽  
pp. 1535 ◽  
Author(s):  
Francesco Calise ◽  
Massimo D’Accadia ◽  
Carlo Barletta ◽  
Vittoria Battaglia ◽  
Antun Pfeifer ◽  
...  

Energy ◽  
2017 ◽  
Vol 141 ◽  
pp. 1750-1763 ◽  
Author(s):  
Na Deng ◽  
Rongchang Cai ◽  
Yuan Gao ◽  
Zhihua Zhou ◽  
Guansong He ◽  
...  

2014 ◽  
Vol 48 ◽  
pp. 290-299 ◽  
Author(s):  
Annamaria Buonomano ◽  
Francesco Calise ◽  
Gabriele Ferruzzi ◽  
Laura Vanoli

2021 ◽  
Vol 12 (1) ◽  
pp. 2
Author(s):  
Shayan Naderi ◽  
Simon Heslop ◽  
Dong Chen ◽  
Iain MacGill ◽  
Gloria Pignatta

Air conditioning is responsible for a considerable proportion of households’ electricity bills. During summer afternoons when households usually run their air conditioners, the retail time-of-use electricity tariffs are highest, and there is a peak demand in the electricity network. Pre-cooling is a method to shift air conditioning demand from peak hours to hours with lower demand and cheaper electricity tariffs. In this research, the pre-cooling potential of nine different types of residential housing in Sydney constructed with different star ratings and construction weights is evaluated. Star rating is the method to represent the annual heating and cooling requirements of buildings in Australia. Results highlight that pre-cooling produces cost saving for most of the days in 6-star and 8-star buildings. For 2-star buildings, pre-cooling sometimes leads to higher electricity costs. Moreover, pre-cooling improves thermal comfort, especially in 2-star light and medium weight buildings.


2021 ◽  
Vol 312 ◽  
pp. 06003
Author(s):  
Franz Bianco Mauthe Degerfeld ◽  
Ilaria Ballarini ◽  
Giovanna De Luca ◽  
Vincenzo Corrado

The EN ISO 52016-1 standard presents a new simplified dynamic calculation procedure, whose aim is to provide an accurate energy performance assessment without excessively increasing the number of data required. The Italian National Annex to EN ISO 52016-1, currently under development, provides some improvements to the hourly calculation method; despite many works can be found in literature on the hourly model of EN ISO 52016-1, the National Annexes application has not been sufficiently analysed yet. The aim of the present work is to assess the main improvements introduced by the Italian National Annex and to compare the main results, in terms of energy need for space heating and cooling. To this purpose, an existing building representative of the Italian office building stock in Northern Italy was selected as a case study. The energy simulations were carried out considering both continuous and reduced operation of the HVAC systems. The options specified in the Italian National Annex were firstly applied one by one, and then all together. The variation of the energy need compared to the international base procedure is finally quantified. For the premises and the scope above discussed, the present work is intended to enhance the standardisation activity towards the adoption of more accurate and trustable calculation methods of the building energy performance.


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