scholarly journals Numerical Optimization of a Single Bunch of NiTi Wires to be Placed in an Elastocaloric Experimental Device: Preliminary Results

2021 ◽  
Vol 7 (5) ◽  
pp. 67
Author(s):  
Luca Cirillo ◽  
Adriana Farina ◽  
Adriana Greco ◽  
Claudia Masselli
Keyword(s):  
Numerical Optimization ◽  
Air Conditioning ◽  
Pressure Field ◽  
Fluid Velocity ◽  
Heat Transfer Fluid ◽  
Cooling Power ◽  
Mass Unit ◽  
Environmental Conditioning ◽  
Practical Tool ◽  
Niti Wires

Italy has not yet presented to the scientific community any elastocaloric prototype suitable for refrigeration/air conditioning. The SUSSTAINEBLE project was born from the idea to build a demonstrative elastocaloric prototype for environmental conditioning. The prototype is planned to be rotary and composed by a few bunches of elastocaloric wires crossed by air as heat transfer fluid. Many are the parameters to be investigated before the realization of the device. A numerical practical tool would help to easily optimize the prototype. In this paper a two-dimensional tool of a single bunch of elastocaloric wires based on finite-element method is introduced; it can reproduce step by step the velocity and the pressure field of fluid to predict more accurately the solid-to-fluid heat exchange. The results of a test campaign mostly focused on the optimization of the frequency of the cycle, fluid velocity and the distance between the elastocaloric wires are presented. The results reveal that: (i) 0.12 Hz as frequency; (ii) 7 m s−1 as velocity; (iii) 1.0 mm as optimal wire distance, would better satisfy the trade-off existing in the maximization of temperature span and cooling power per mass unit: 23.7 K and 311.97 W kg−1 are the values achieved, respectively.

scholarly journals Absorption and adsorption chillers applied to air conditioning systems

2010 ◽  
Vol 31 (2) ◽  
pp. 77-94 ◽  
Author(s):  
Agnieszka Kuczyńska ◽  
Władysław Szaflik
Keyword(s):  
Heat Source ◽  
Air Conditioning ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Geothermal Heat ◽  
Pump System ◽  
Desorption Process ◽  
Heat Pump System ◽  
Adsorption Chiller ◽  
Air Conditioning Systems

Absorption and adsorption chillers applied to air conditioning systemsThis work presents an application possibility of sorption refrigerators driven by low temperature fluid for air conditioning of buildings. Thermodynamic models were formulated and absorption LiBr-water chiller with 10 kW cooling power as well as adsorption chiller with silica gel bed were investigated. Both of them are using water for desorption process with temperatureTdes= 80 °C. Coefficient of performance (COP) for both cooling cycles was analyzed in the same conditions of the driving heat source, cooling waterTc= 25 °C and temperature in evaporatorTevap= 5 °C. In this study, the computer software EES was used to investigate the performance of absorption heat pump system and its behaviour in configuration with geothermal heat source.

The Analysis of Modifications in Cooling Systems for High-Performance Data Centers. A Case Study

2017 ◽  
Author(s):  
Artur Rusowicz ◽  
Adam Ruciński ◽  
Rafał Laskowski
Keyword(s):  
Air Conditioning ◽  
High Performance ◽  
Energy Savings ◽  
Cooling System ◽  
Capital Expenditure ◽  
Cooling Power ◽  
Power Demand ◽  
Excessive Heat ◽  
Refrigeration Equipment ◽  
Payback Time

One of main issues concerning server room operation is appropriate cooling of electronic modules to prevent excessive heat generation resulting in their damage. Since high cooling powers are required, precision air conditioning systems are used that are specially designed for cooling server and equipment rooms, server cabinets, etc. These devices require very large energy supplies. The paper proposes an upgrade of a cooling system for three server rooms in which refrigeration equipment with a cooling power of 1.873 MW is installed. The average actual cooling power demand is 890 kW, and some units work as a standby. Thir-eight direct-evaporation air-conditioning cabinets are installed. The refrigerant is R407C. The devices have been operated for 14 years; therefore, the refrigeration equipment should be replaced with modern units. The paper compares three approaches: replacing the units with similar ones based on newer technology, introducing contained aisle configurations of rack cabinets and units based on newer technology with additional EconoPhase modules. The application of free cooling was not analyzed since mounting additional heat exchangers was impossible (due to the lack of space and limited roof loading capacity). The paper provides capital and operating costs of the solutions. The introduction of up-to-date units and replacing condensers resulted in lowering the electric power demand by 16%. The simple payback time (SPBT) of this solution is 18.8 years. The energy savings achieved through the second solution (contained aisle configurations of rack cabinets) amount to 37.8%, with SPBT equal to 8.38 years. Variant III, consisting in using modern units with additional EconoPhase modules, significantly improves energy savings (48.3%) but it requires large capital expenditure, with simple payback time of 12.1 years.

scholarly journals Active magnetocaloric heat pipes provide enhanced specific power of caloric refrigeration

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Lena Maria Maier ◽  
Patrick Corhan ◽  
Alexander Barcza ◽  
Hugo A. Vieyra ◽  
Christian Vogel ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipes ◽  
Heat Transfer Fluid ◽  
Specific Power ◽  
Cooling Power ◽  
Cycle Frequency ◽  
Cooling Systems ◽  
Cooling Unit ◽  
Order Of Magnitude ◽  
Almost All

Abstract Today almost all refrigeration systems are based on compressors, which often require harmful refrigerants and typically reach 50% of the Carnot efficiency. Caloric cooling systems do not need any detrimental fluids and are expected to reach 60–70% of the Carnot limit. Current caloric systems utilise the active magnetocaloric regeneration principle and are quite cost-intensive, as it is challenging to achieve large cycle frequencies and thus high specific cooling powers with this principle. In this work, we present an alternative solution where the heat transfer from the heat exchangers to the caloric material is predicated on condensation and evaporation of a heat transfer fluid. Using thermal diodes, a directed heat flow is generated. Thereby we were able to build a cooling unit achieving a specific cooling power of 12.5 W g−1 at a cycle frequency of 20 Hz, which is one order of magnitude larger than the state-of-the-art.

scholarly journals Functioning Efficiency of the Central Air-Conditioning System on the Selected Example

2020 ◽  
Vol 3 (1) ◽  
pp. 41-55
Author(s):  
Nikodem Szlązak ◽  
Justyna Swolkień
Keyword(s):  
Air Conditioning ◽  
Cooling Water ◽  
Electricity Consumption ◽  
Cooling Capacity ◽  
Total Power ◽  
Hard Coal ◽  
Cooling Power ◽  
Airflow Rate ◽  
Air Temperatures ◽  
Reduce Electricity Consumption

AbstractOne of the particularly significant threats during exploitation is the climatic threat, which is associated with an increase in the overall costs that are allocated to combating it. The rise in the virgin temperature of the rock mass by 1oC increases the demand for the required cooling capacity to be taken from the air. The publication assesses the effectiveness of the air-conditioning installation by testing its operation on a selected example. The assessment of the efficiency of the air-conditioning installation for a selected hard coal mine showed that none of the five tested coolers achieved the maximum assumed rated power. The use of total power (7.5 MW) in mining excavations was less than 50% and amounted to η = 0.472%. The research showed that the main reason for obtaining low cooling parameters is the inability to locate them in the place of the highest air temperatures. The other problem is an insufficient airflow rate of cooling water supplied to the coolers at too high temperature. The above considerations indicated that the cooling power from built-in air- conditioning systems is not properly and effectively used. Improving the efficiency of its functioning is possible by proceeding research that will eliminate the above factors and by using air conditioning equipment, taking into account the periodic audit of their work to reduce electricity consumption.

Dynamic Simulation of an Ejector-Based Cooling System for Residential Solar Air-Conditioning

2012 ◽  
Author(s):  
Stefano Gavioli ◽  
Jean-Marie Seynhaeve ◽  
Yann Bartosiewicz
Keyword(s):  
Dynamic Simulation ◽  
Air Conditioning ◽  
Cooling System ◽  
Geographic Location ◽  
Hot Water ◽  
Cooling Power ◽  
Dynamic Simulation Model ◽  
Hot Season ◽  
Transient Thermal ◽  
Ejector Cycle

A smart and sustainable way to produce cooling power during the hot season is through thermal activated compression. One of the most promising technology is the ejector cycle. An experimental machine based on this technology has been designed and built at Université Catholique de Louvain (UCL). This study presents a dynamic simulation model of a full house incorporating solar collectors to produce domestic hot water and to feed an ejector-based solar air-conditioning machine. The model takes into account geographic location, transient thermal house behaviour, and also integrates a performance map of the ejector cycle based on real measurement campaign. Different types of collectors and storage sizes have been studied as well. In this paper, the developed model is used to analyze and optimize operation and strategy of hot water production and air conditioning. Results show that the full solar solution may cover low energy house needs.

Dynamic Character Study on Cool Thermal Energy Storage Process of Storage Tank for Air-Conditioning System

2012 ◽  
Vol 433-440 ◽  
pp. 1052-1056
Author(s):  
Xiao Yan Li ◽  
Yan Yan Wu ◽  
Zhi Fen Cen
Keyword(s):  
Energy Storage ◽  
Flow Rate ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Tank ◽  
Air Conditioning ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Air Conditioning System ◽  
Appreciable Change

Mathematical model of the storage tank for air-conditioning condition was established, the dynamics character of a new type of PCM in the storage tank was studied., and the model was numerical simulated by the method of heat capacity. Effects of flow rate and inlet temperature of heat transfer fluid (HTF) on charging process of the storage tank were obtained. The results show that no appreciable change in the total cold thermal energy storage is observed for the increase of flow rate, whereas the improvement of the total cold thermal energy storage due to the decrease of inlet temperature is detectable, when cold storage is finished during low peak of electricity, the best inlet temperature of storage tank is at 2°C-3°C.

scholarly journals Performance Evaluation of Photovoltaic Solar Air Conditioning

2016 ◽  
Vol 53 (6) ◽  
pp. 29-36
Author(s):  
A. Snegirjovs ◽  
P. Shipkovs ◽  
K. Lebedeva ◽  
G. Kashkarova ◽  
L. Migla ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Air Conditioning ◽  
Large Scale ◽  
Ambient Air ◽  
Hot Water ◽  
Energy Output ◽  
Cooling Power ◽  
Energy Unit ◽  
Technical Data ◽  
Reverse Mode

Abstract Information on the electrical-driven solar air conditioning (SAC) is rather scanty. A considerable body of technical data mostly concerns large-scale photo-voltaic solar air conditioning (PV-SAC) systems. Reliable information about the energy output has arisen only in recent years; however, it is still not easily accessible, and sometimes its sources are closed. Despite these facts, solar energy researchers, observers and designers devote special attention to this type of SAC systems. In this study, performance evaluation is performed for the PV-SAC technology, in which low-power (up to 15 kWp of cooling power on average) systems are used. Such a system contains a PV electric-driven compression chiller with cold and heat sensible thermal storage capacities, and a rejected energy unit used for preheating domestic hot water (DHW). In a non-cooling season, it is possible to partly employ the system in the reverse mode for DHW production. In this mode, the ambient air serves as a heat source. Besides, free cooling is integrated in the PV-SAC concept.

scholarly journals Fabrication and Performance Evaluation of Cold Thermal Energy Storage Tanks Operating in Water Chiller Air Conditioning System

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4159
Author(s):  
Xuan Vien Nguyen
Keyword(s):  
Heat Transfer ◽  
Cold Storage ◽  
Storage Tank ◽  
Air Conditioning ◽  
Thermal Storage ◽  
Hot Water ◽  
Operating Costs ◽  
Heat Transfer Fluid ◽  
Storage Tanks ◽  
Air Conditioning System

In this study, cold and thermal storage systems were designed and manufactured to operate in combination with the water chiller air-conditioning system of 105.5 kW capacity, with the aim of reducing operating costs and maximizing energy efficiency. The cold storage tank used a mixture of water and 10 wt.% glycerin as a phase-change material (PCM), while water was used as heat transfer fluid (HTF). The cold storage heat exchanger was made of polyvinyl chloride (PVC). On the other hand, the thermal storage tank used water as the storage fluid with a capacity of 50 L of hot water per hour. The thermal storage did not use a pump for water transfer through the heat exchanger, so as to save energy and operating costs. In this paper, the operating parameters of the cold and thermal storage tanks are shown according to the results of experimental research, including the temperatures of cooling and heating load, heat transfer fluid, and cold storage material during the discharge process, as well as the discharge duration. The system assisted the air conditioner in cooling the internship workshop space at the university with an area of 400 m2, contributing to a remarkable reduction in air-conditioning system operating costs during the daytime. Furthermore, the system recovered waste heat from the compressor of the water chiller, and a thermal storage system was successfully built and operated, providing 50 L of hot water at a temperature of 60 °C per hour to serve the everyday needs of school students. This design was suitable for the joint operation of cold and thermal storage tanks and the water chiller air-conditioning system for cooling and heating applications.

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