scholarly journals Numerical optimization of a multistage sorption compressor

2021 ◽  
Vol 2116 (1) ◽  
pp. 012113
Author(s):  
A Hamersztein ◽  
A Davidesko ◽  
N Tzabar
Keyword(s):  
Numerical Model ◽  
High Pressures ◽  
Cooling System ◽  
Cell Envelope ◽  
High Reliability ◽  
Pressure Fluctuations ◽  
Electric Heater ◽  
Operational Parameters ◽  
Operating Life ◽  
Dimensional Parameters

Abstract Sorption compressors are driven by thermal cycles and have no moving parts, excluding some passive check valves. Such compressors are suitable for powering Joule-Thomson (JT) cryocoolers and can provide reliable and vibration free active cooling system with a potential for high reliability and long operating life. The thermal cycle consists of cooling and heating a sorbent material which is installed in a sorption cell, where the heating is obtained by an inner electric heater and cooling is obtained by the surrounding via the sorption cell envelope. The investigation and optimization of the sorption cells were conducted in previous work, at steady state conditions, by a one-dimensional heat and mass transfer numerical model. The current paper presents a dynamic numerical model of sorption compressors which consist of several sorption cells. The numerical model allows one to three compression stages, with any number of sorption cells at each stage. The model enables the investigation of dimensional parameters and operational parameters, and provides the low and high pressures, pressure fluctuations, and compressor’s efficiency. The current investigation focuses on a three-stage compressor for nitrogen, with low and high pressures of 0.2 and 8 MPa, respectively, and a mass flow rate of about 11 mg/s.

Numerical Evaluation and Optimization of the Combined Solar Thermal and Electric Desiccant Cooling System

2009 ◽  
Author(s):  
Napoleon Enteria ◽  
Hiroshi Yoshino ◽  
Akira Satake ◽  
Akashi Mochida ◽  
Ryuichiro Yoshie ◽  
...  
Keyword(s):  
System Performance ◽  
Solar Collector ◽  
Numerical Evaluation ◽  
Cooling System ◽  
Electric Energy ◽  
System Optimization ◽  
Solar Thermal ◽  
Electric Heater ◽  
Operational Parameters ◽  
Performance Reduction

Novel solar thermal desiccant cooling system has been developed. Experimental operation and evaluation of the system was conducted. System optimization and parametric investigation are so important for the improvement of system performance. However, inasmuch as evaluation through experimentation is time consuming and very expensive, numerical model is made and developed for the system. The developed model is implemented in TRNSYS program. The model is validated using the experimental data of the system. Based on the result of the numerical evaluation is conducted the area of the installed solar collector area must be reduced to 8m2. The needed electric heater heating operation is 2 hours. Reduction of the solar collector inclination angle to 30° improved the solar energy collection. Improvement of the desiccant wheel dehumidification rate increased the system total performance. Increasing the heat exchanger (HEX 2) efficiency lowered the supply air temperature with improvement of system performance. Reduction of the system electric energy consumption increased the system electric COP (ECOP). These results of the study are of great importance for the improvement of the design of the developed system, operational procedure, and performance. The relationship and effects of the variables in the study are applicable for other researches seeking the effects of the operational parameters for the solar thermal desiccant cooling system design and processes.

Heat dissipation system based on electromagnetic driven rotational flow of liquid metal coolant

2021 ◽  
pp. 1-14
Author(s):  
Lei Wang ◽  
Xudong Zhang ◽  
Dr. Jing Liu ◽  
Yixin Zhou
Keyword(s):  
Liquid Metal ◽  
Thermal Resistance ◽  
Heat Dissipation ◽  
High Efficiency ◽  
Cooling System ◽  
Electric Heater ◽  
Power Relationship ◽  
Rotational Flow ◽  
Large Power ◽  
Dissipation System

Abstract Liquid metal owns the highest thermal conductivity among all the currently available fluid materials. This property enables it to be a powerful coolant for the thermal management of large power device or high flux chip. In this paper, a high-efficiency heat dissipation system based on the electromagnetic driven rotational flow of liquid metal was demonstrated. The velocity distribution of the liquid metal was theoretically analyzed and numerically simulated. The results showed that the velocity was distributed unevenly along longitudinal section and the maximum velocity appears near the anode. On the temperature distribution profile of the heat dissipation system, the temperature on the electric heater side was much higher than the other regions and the role of the rotated liquid metal was to homogenize the temperature of the system. In addition, the thermal resistance model of the experimental device was established, and several relationships such as thermal resistance-power curve were experimentally measured. The heating power could be determined from the temperature-power relationship graph once the maximum control temperature was given. The heat dissipation method introduced in the paper provides a novel way for fabricating compact chip cooling system.

Investigation of Parameter Effect to Performance of Battery's Cooling System

2012 ◽  
Vol 538-541 ◽  
pp. 2015-2019
Author(s):  
Zhen Zhe Li ◽  
Xiao Ming Pan ◽  
Ming Ren ◽  
Mei Qin Li ◽  
Gui Ying Shen
Keyword(s):  
Energy Consumption ◽  
Fuel Cell ◽  
Numerical Model ◽  
Electric Vehicle ◽  
Hybrid Electric Vehicle ◽  
Cooling System ◽  
Analysis Model ◽  
Hybrid Electric

With the heightened concern for energy consumption and environment conservation, the interest on fuel cell HEV (hybrid electric vehicle) has been greatly increased. In this study, a numerical model for the cooling system of batteries was constructed. Using the constructed analysis model, the material of the cartridge and the cartridge width were checked for improving the performance of the cooling system of batteries. The performance was changed by using different cartridge material, and the cartridge width also has an effect to the performance of the cooling system of batteries as shown in the analysis results. The constructed model and method can be used to investigate the performance of the cooling system of batteries.

Unsteady Flow Structure on a Centrifugal Pump: Experimental and Numerical Approaches

2002 ◽  
Author(s):  
Jose´ Gonza´lez ◽  
Carlos Santolaria ◽  
Eduardo Blanco ◽  
Joaqui´n Ferna´ndez
Keyword(s):  
Numerical Model ◽  
Centrifugal Pump ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Side Wall ◽  
Relative Effect ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
Blade Passing Frequency ◽  
Wide Range

Both experimental and numerical studies of the unsteady pressure field inside a centrifugal pump have been carried out. The unsteady patterns found for the pressure fluctuations are compared and a further and more detailed flow study from the numerical model developed will be presented in this paper. Measurements were carried out with pressure transducers installed on the volute shroud. At the same time, the unsteady pressure field inside the volute of a centrifugal pump has been numerically modelled using a finite volume commercial code and the dynamic variables obtained have been compared with the experimental data available. In particular, the amplitude of the fluctuating pressure field in the shroud side wall of the volute at the blade passing frequency is successfully captured by the model for a wide range of operating flow rates. Once the developed numerical model has shown its capability in describing the unsteady patterns experimentally measured, an explanation for such patterns is searched. Moreover, the possibilities of the numerical model can be extended to other sections (besides the shroud wall of the volute), which can provide plausible explanations for the dynamic interaction effects between the flow at the impeller exit and the volute tongue at different axial positions. The results of the numerical simulation are focused in the blade passing frequency in order to study the relative effect of the two main phenomena occurring at that frequency for a given position: the blade passing in front of the tongue and the wakes of the blades.

Relative Cooling: Part II — Design Considerations and Efficiency

2001 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Cooling System ◽  
High Reliability ◽  
Difficult Problem ◽  
Turbine Engines ◽  
Air Cooling ◽  
Gas Turbine Engines ◽  
Coolant Pump ◽  
Cooling Systems

Abstract Cooling systems with liquid for gas turbine engines that use the relative motion of the engine stator with respect to the rotor for actuating the coolant pump can be encapsulated within the engine rotor. In this manner, the difficult problem of sealing stator/rotor interfaces at high temperature, pressure and relative velocity is circumvented. A first generation of such cooling systems could be manufactured using existing technologies and would boost the thermal efficiency of gas turbine engines by more than 2% compared to recent designs that use advanced air-cooling methods. Later, relative cooling systems could increase the thermal efficiency of gas turbine engines by 8%–11% by boosting the temperatures at turbine inlet to stoichiometric levels and recovering most of the heat extracted from turbine during cooling. The appreciated high reliability of this cooling system will allow widespread use for aerospace propulsion.

Updating the Helicopter Gas Turbine Engine Mass Model for the Defining of the Turboshaft Engine Optimal Operating Cycle Parameters

2019 ◽  
Author(s):  
D. S. Kalabuhov ◽  
V. A. Grigoriev ◽  
A. O. Zagrebelnyi ◽  
D. S. Diligensky
Keyword(s):  
Gas Turbine ◽  
Power Unit ◽  
Cooling System ◽  
Gas Turbine Engine ◽  
Parameters Optimization ◽  
Operational Parameters ◽  
Mass Model ◽  
Operating Cycle ◽  
Turbine Engine ◽  
Turboshaft Engine

Abstract The article describes the adjusted parametrical turboshaft gas turbine engine mass model that is applied for the helicopter engine operating cycle parameters optimization during a conceptual engineering. During the operation of the take-off mass, which indirectly characterizes the cost of materials for the entire designed aircraft system, one of the main components which determines the coordination of the helicopter and its engine parameters is a mass of the gas turbine power unit. Moreover, during the parametrical studies the designed mass of a power unit should be defined by the parameters of a gas turbine engine; however, this type of dependencies is not that well enough studied for today. Therefore the evaluation of the dependency between the engine mass and its operational parameters is performed by using either generalized statistical data for existing designs or by parametrical mass models since there is nothing more precise up to date. However as new types of gas turbine engines appear it is required to update the values of parametrical model coefficients. This article describes the influence of different cooling system units on the engine mass and also clarifies the coefficients that specify the engine mass advance by introducing the structural-technological measures. The last one is highly dependent on the designed gas turbine engine (GTE) serial production year. It also has been proposed to represent some coefficients that are used in the model as dependencies of the main operational parameters. This has allowed to perform the parametrical study and to gain predictive solutions in correspondence to the modern engine design level.

Development of Technologies on Innovative Simplified Nuclear Power Plant Using High-Efficiency Steam Injectors: Part 10—Application to a Small District-Heating Reactor

2006 ◽  
Author(s):  
Tadashi Narabayashi ◽  
Yoichiro Shimazu ◽  
Toshihiko Murase ◽  
Masatoshi Nagai ◽  
Michitsugu Mori ◽  
...  
Keyword(s):  
Power Plant ◽  
Direct Contact ◽  
Cooling System ◽  
High Reliability ◽  
District Heating ◽  
Water Jet ◽  
Hot Water ◽  
Feed Water ◽  
District Heating System ◽  
Core Cooling

A steam injector (SI) is a simple, compact and passive pump and also acts as a high-performance direct-contact compact heater. This provides SI with capability to use as a passive ECCS pump and also as a direct-contact feedwater heater that heats up feedwater by using extracted steam from the turbine. In order to develop a high reliability passive ECCS pump and a compact feedwater heater, it is necessary to quantify the characteristics between physical properties of the flow field. We carried out experiments to observe the internal behavior of the water jet as well as measure the velocity of steam jet using a laser Doppler velocimetry. Its performance depends on the phenomena of steam condensation onto the water jet surface and heat transfer in the water jet due to turbulence on to the phase-interface. The analysis was also conducted by using a CFD code with the separate two-phase flow models. With regard to the simplified feed-water system, size of four-stage SI system is almost the same as the model SI that had done the steam and water test that pressures were same as that of current ABWR. The authors also conducted the hot water supply system test in the snow for a district heating. With regard to the SI core cooling system, the performance tests results showed that the low-pressure SI core cooling system will decrease the PCT to almost the same as the saturation temperature of the steam pressure in a pressure vessel. As it is compact equipment, SI is expected to bring about great simplification and materials-saving effects, while its simple structure ensures high reliability of its operation, thereby greatly contributing to the simplification of the power plant for not only an ABWR power plant but also a small PWR/ BWR for district heating system.

Experimental Analysis of Newly Designed Solar Assisted Single Effect Absorption Cooling System of 5.25 kW Cooling Capacity for Domestic Use

2015 ◽  
Vol 787 ◽  
pp. 32-36 ◽  
Author(s):  
V.Boopathi Raja ◽  
V. Shanmugam
Keyword(s):  
Cooling System ◽  
Cooling Capacity ◽  
Hot Water ◽  
Operational Parameters ◽  
Water Storage Tank ◽  
Absorption Cooling ◽  
Domestic Use ◽  
Single Effect ◽  
Absorption Cooling System ◽  
Vapour Compression

Many research studies have been carried out to develop small capacity absorption cooling systems as an alternative to conventional vapour compression refrigeration (VCR) systems with respect to performance and economic aspects. The aim of this work is to design a solar assisted single effect absorption cooling system of 5.25 kW cooling capacity to cool a room having floor area of 15 m2. Based on the design, an experimental setup is constructed and operated by supplying heat to the generator using solar energy. The performance analysis of the cooling system is carried out by measuring the various operational parameters. The minimum cooling temperature of 16°C is observed in the evaporator and maximum COP of 0.9 is obtained when the hot water storage tank reaches 90°C. As per this new design, the operational cost is minimized and the COP obtained is slightly higher when compared to that of earlier similar works.

Computational Analysis of Nanofluid Cooling of High Concentration Photovoltaic Cells

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Z. Xu ◽  
C. Kleinstreuer
Keyword(s):  
Reynolds Number ◽  
Energy Use ◽  
Volume Fraction ◽  
Cooling System ◽  
Optimal Parameter ◽  
Photovoltaic Cells ◽  
System Efficiency ◽  
Operational Parameters ◽  
High Concentration ◽  
Temperature Range

High concentration photovoltaic devices require effective heat rejection to keep the solar cells within a suitable temperature range and to achieve acceptable system efficiencies. Various techniques have been developed to achieve these goals. For example, nanofluids as coolants have remarkable heat transfer characteristics with broad applications; but, little is known of its performance for concentration photovoltaic cooling. Generally, a cooling system should be designed to keep the system within a tolerable temperature range, to minimize energy waste, and to maximize system efficiency. In this paper, the thermal performance of an Al2O3-water cooling system for densely packed photovoltaic cells under high concentration has been computationally investigated. The model features a representative 2D cooling channel with photovoltaic cells, subject to heat conduction and turbulent nanofluid convection. Considering a semi-empirical nanofluid model for the thermal conductivity, the influence of different system design and operational parameters, including required pumping power, on cooling performance and improved system efficiency has been evaluated. Specifically, the varied system parameters include the nanoparticle volume fraction, the inlet Reynolds number, the inlet nanofluid temperature, and different channel heights. Optimal parameter values were found based on minimizing the system's entropy generation. Considering a typical 200-sun concentration, the best performance can be achieved with a channel of 10 mm height and an inlet Reynolds number of around 30,000, yielding a modest system efficiency of 20%. However, higher nanoparticle volume fractions and lower nanofluid inlet temperatures further improve the cell efficiency. For a more complete solar energy use, a combined concentration photovoltaic and thermal heating system are suggested.

Simulation and Optimization of a Concentrated Photovoltaic System

2005 ◽  
Vol 128 (2) ◽  
pp. 139-145 ◽  
Author(s):  
I. Mahderekal ◽  
C. K. Halford ◽  
R. F. Boehm
Keyword(s):  
Numerical Model ◽  
Conversion Efficiency ◽  
Cooling System ◽  
Photovoltaic System ◽  
Weather Data ◽  
Entire System ◽  
Simulation And Optimization ◽  
Size Number ◽  
Input Parameters ◽  
Fan Speed

Reported here is the development, using results of analysis and experiments, and optimization of a numerical model for a concentrated photovoltaic system. Models for the two major components of the system (cooling system and receiver) are developed separately from one another and then linked to simulate the performance for the entire system. The model is linked to yearly weather data and the optimization routines included in MATLAB are then used to select the input parameters (pump size, number of radiators, fan speed, etc.) which maximize the solar to electrical conversion efficiency of the system.

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