scholarly journals Applying the scalability apparatus to estimate the thermal efficiency of a single finned tube

2021 ◽  
Vol 2057 (1) ◽  
pp. 012014
Author(s):  
A A Gizzatullina ◽  
O V Mishchenkova ◽  
F N Pushkarev
Keyword(s):  
Cooling System ◽  
Aerodynamic Resistance ◽  
Conjugate Problem ◽  
Finned Tube ◽  
Cooling Process ◽  
System Operation ◽  
Integral Characteristics ◽  
Parametric Studies ◽  
Numerical Coefficient ◽  
Cooling Element

Abstract The paper explores the possibility of scaling the integral parameters of the cooling system operation using the working elements with the length from 0.01 to 0.5 m. Numerical solution of the conjugate problem of external aeromechanics, internal hydrodynamics and heat exchange is carried out. Parametric studies of the cooling process and aerodynamic resistance of finned tubular elements of various lengths are performed. As a result of generalization and unification of the computational experimental data, a numerical coefficient has been obtained to calculate the necessary integral characteristics for a cooling element of the assigned length.

Cooling Efficiencies of a NiTi-Based Cooling Process

2013 ◽  
Author(s):  
Marvin Schmidt ◽  
Andreas Schütze ◽  
Stefan Seelecke
Keyword(s):  
Solid State ◽  
Thermodynamic Analysis ◽  
Cooling System ◽  
Analysis Method ◽  
Efficiency Ratio ◽  
Cooling Process ◽  
First Results ◽  
Work Input ◽  
Underlying Mechanisms ◽  
The Impact

Energy saving and environmental protection are topics of growing interest. In the light of these aspects alternative refrigeration principles become increasingly important. Shape memory alloys (SMA), especially NiTi alloys, generate a large amount of latent heat during solid state phase transformations, which can lead to a significant cooling effect in the material. These materials do not only provide the potential for an energy-efficient cooling process, they also minimize the impact on the environment by reducing the need for conventional ozone-depleting refrigerants. Our paper, presenting first results obtained in a project within the DFG Priority Program SPP 1599 “Ferroic Cooling”, focuses on the thermodynamic analysis of a NiTi-based cooling system. We first introduce a suitable cooling process and subsequently illustrate the underlying mechanisms of the process in comparison with the conventional compression refrigeration system. We further introduce a graphical solution to calculate the energy efficiency ratio of the system. This thermodynamic analysis method shows the necessary work input and the heat absorption of the SMA in stress/strain- or temperature/entropy-diagrams, respectively. The results of the calculations underline the high potential of this solid-state cooling methodology.

scholarly journals Measurements of Flat-Plate Milk Coolers

2014 ◽  
Vol 62 (5) ◽  
pp. 1057-1064
Author(s):  
Vlastimil Nejtek ◽  
Jiří Fryč ◽  
Josef Los
Keyword(s):  
Flat Plate ◽  
Flow Rate ◽  
Cost Reduction ◽  
Cooling System ◽  
Cooling Water ◽  
Electricity Consumption ◽  
Measured Data ◽  
Cooling Process ◽  
Throttle Valve ◽  
Plate Cooler

Measuring in laboratory conditions was performed with the aim to collect a sufficient quantity of measured data for the qualified application of flat-plate coolers in measuring under real operating conditions. The cooling water tank was filled with tap water; the second tank was filled with water at a temperature equivalent to freshly milked milk. At the same time, pumps were activated that delivered the liquids into the flat-plate cooler where heat energy was exchanged between the two media. Two containers for receiving the run-out liquid were placed on the outputs from the cooler; here, temperature was measured with electronic thermometer and volume was measured with calibrated graduated cylinder. Flow rate was regulated both on the side of the cooling fluid and on the side of the cooled liquid by means of a throttle valve. The measurements of regulated flow-rates were repeated several times and the final values were calculated using arithmetic average. To calculate the temperature coefficient and the amount of brought-in and let-out heat, the volume measured in litres was converted to weight unit. The measured values show that the volume of exchanged heat per weight unit increases with the decreasing flow-rate. With the increasing flow-rate on the throttled side, the flow-rate increases on the side without the throttle valve. This phenomenon is caused by pressure increase during throttling and by the consequent increase of the diameter of channels in the cooler at the expense of the opposite channels of the non-throttled part of the circuit. If the pressure is reduced, there is a pressure decrease on the external walls of opposite channels and the flow-rate increases again. This feature could be utilised in practice: a pressure regulator on one side could regulate the flow-rate on the other side. The operating measurement was carried out on the basis of the results of laboratory measurements. The objective was to determine to what extent the use of flat-plate coolers under specific conditions results in cost reduction and improved milk cooling process. The measurement was performed in several cycles. The first measurement took place in the existing system without the use of the flat-plate cooler. The volume of drawn milk was monitored throughout the milking process along with its temperature, temperature in the tank and electricity consumption of the cooling system. At the second stage, the flat-plate cooler was introduced into the cooling process, which was followed by monitoring the milk and cooling water volume, their temperature, temperature in the tank and electricity consumption of the cooling system. The measured data indicate considerable power cost reduction if upstream flat-plate coolers are applied.

scholarly journals The Study of Cooling Process on Runout Table by Simulation Method

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Anan Suebsomran ◽  
Suthep Butdee
Keyword(s):  
Heat Conduction ◽  
Cooling System ◽  
Fluid Velocity ◽  
Translational Motion ◽  
Cooling Water ◽  
Transient Heat Conduction ◽  
Cooling Process ◽  
Strip Steel ◽  
Difference Formula ◽  
Runout Table

This research aims to achieving the effective cooling parameter on the runout table (ROT) of strip steel in hot rolling process. The 2-dimensional transient heat conduction is developed including the external force convection and heat source due to translational motion. The material property, boundary, and initial condition are defined and bounded to model geometry. The strip velocity, cooling water temperature, and external fluid velocity are chosen for the influent parameters during cooling process at ROT. To find the optimality of cooling operating requirement, simulation study is conducted throughout this research. To reach the objective of optimal cooling consumption at ROT, temperature distribution in the strip steel during cooling governs by the form of heat transfer equation. To solve 2-dimensional transient heat conduction by numerical methods, the backward difference formula (BDF) applies to discretization of partial differentiation equation (PDE). The parallel sparse direct linear solver (PARDISO) and conjugate gradients method are comparatively applied to computation in linear algebraic equation. The simulation studies are divided into 12 case studies with three variations subjected to cooling conditions at ROT. From simulation results, the range of such three variations can be identified in relation to economic cooling system and desired quality of products.

Flow Analysis and Experimental Study on a Frost Reduction Method for Heat Exchangers

2020 ◽  
Vol 25 (3) ◽  
pp. 9-16
Author(s):  
Gwon-Seok Sun
Keyword(s):  
Experimental Study ◽  
Heat Exchangers ◽  
Reduction Method ◽  
Cooling System ◽  
Flow Analysis ◽  
Finned Tube ◽  
Cooling Efficiency ◽  
Frost Formation ◽  
Air Blast ◽  
New Type

Frosting on the surface of a heat exchanger degrades its cooling efficiency in a cooling system. In this study, frost flow analysis is performed for frost reduction. A new type of air blast refrigerator is designed for reducing frost formation in its finned tube. Experimental results of the frost formation in the air blast refrigerator are presented. The main difference between the proposed and conventional air blast refrigerators is the flow of air through the finned tube. The proposed refrigerator produces less frost than the conventional refrigerators.

scholarly journals Influence of system operation on the design and performance of a direct ground-coupled cooling system

2020 ◽  
pp. 110709
Author(s):  
Taha Arghand ◽  
Saqib Javed ◽  
Anders Trüschel ◽  
Jan-Olof Dalenbäck
Keyword(s):  
Cooling System ◽  
System Operation ◽  
And Performance

Modeling the Cooling Process Path of a Dehumidifying Coil Under Frosting Conditions

2002 ◽  
Vol 124 (6) ◽  
pp. 1182-1191 ◽  
Author(s):  
P. J. Mago ◽  
Dr. S. A. Sherif
Keyword(s):  
Freezing Point ◽  
Finned Tube ◽  
Dew Point ◽  
Actual Process ◽  
Cooling Process ◽  
Demarcation Line ◽  
Large Measure ◽  
Straight Line ◽  
Cooling Coil ◽  
Derived Data

Whenever humid air comes in contact with a cooling coil whose temperature is below both the dew-point of water vapor in air and the freezing point, frost will form. The nature of the frost forming on the coil will depend to a large measure on the psychrometric conditions prevailing inside the freezer and whether the air around the coil is subsaturated or supersaturated. Psychrometric theory and the apparatus-dew-point calculating procedure assume that the cooling process path as the air passes through the coil is a straight-line on the psychrometric chart. The actual path is however a result of a much more complex series of processes and is therefore a curve. While researchers have calculated the actual process path on a dehumidifying coil, none has attempted to do the same for a frosted, multi-row coil. It is believed that determining the actual conditions leaving a given row in a multi-row freezer coil is a crucial step in identifying the coil location in the vicinity of which the transformation from the subsaturated zone to the supersaturated zone occurs. This will prove a key step in identifying a demarcation line between the unfavorable snow-like frost and the more traditional (and more favorable) frost formation patterns. Thus, the objective of this paper is to calculate the air path on an actual industrial-size finned-tube, multi-row coil utilizing experimentally derived data and correlate the shape of the path with the prevailing psychrometric conditions in the freezer in the hope of identifying the demarcation line in question.

Experimental Investigation on the Efficiency of a Control Dependent NiTi-Based Cooling Process

2014 ◽  
Author(s):  
Marvin Schmidt ◽  
Andreas Schütze ◽  
Stefan Seelecke
Keyword(s):  
Energy Efficient ◽  
Cooling System ◽  
Experimental Testing ◽  
Control Process ◽  
Process Variations ◽  
Coefficient Of Performance ◽  
Testing System ◽  
Cooling Process ◽  
Commercial Development ◽  
The Impact

Energy efficient systems and environmentally friendly solutions are the focus of many commercial development projects. Current refrigeration technology carries a significant share of global energy consumption and exploring alternative refrigeration principles has become increasingly important. Shape memory alloys (SMA’s), especially Nickel-Titanium (NiTi) alloys, generate a large amount of latent heat during solid-state phase transformations, which can lead to a significant cooling effect in the material. These materials not only provide the potential for an energy efficient cooling process, they also minimize the impact on the environment by reducing the need for conventional ozone-depleting refrigerants. This paper presents the first experimental results obtained in a project within the DFG Priority Programme SPP 1599 “Ferroic Cooling”. It focuses on the performance of a control-dependent process of a NiTi-based cooling system. First, a suitable cooling process is introduced and the underlying mechanisms of the process are explained. Then different process variations are developed, which influence the efficiency of the cooling process. These process variations are systematically analyzed with a novel, experimental testing system capable of tuning process parameters independently. The testing system is able to measure force, displacement, temperature distribution and heat simultaneously. The coefficient of performance (of the cooling process) can then be determined by which the influence of the control process on the efficiency can be observed.

scholarly journals Next-Generation HVAC: Prospects for and Limitations of Desiccant and Membrane-Based Dehumidification and Cooling

2017 ◽  
Author(s):  
Omar Labban
Keyword(s):  
Cooling System ◽  
System Level ◽  
Device Performance ◽  
Vapor Compression ◽  
Next Generation ◽  
Outdoor Temperature ◽  
Cooling Process ◽  
Vapor Compression System ◽  
Shed Light ◽  
Specific Technology

Recently, next-generation HVAC technologies have gained attention as potential alternatives to the conventional vapor-compression system (VCS) for dehumidification and cooling. Previous studies have primarily focused on analyzing a specific technology or its application to a particular climate. A comparison of these technologies is necessary to elucidate the reasons and conditions under which one technology might outperform the rest. In this study, we apply a uniform framework based on fundamental thermodynamic principles to assess and compare different HVAC technologies from an energy conversion standpoint. The thermodynamic least work of dehumidification and cooling is formally defined as a thermodynamic benchmark, while VCS performance is chosen as the industry benchmark against which other technologies, namely desiccant-based cooling system (DCS) and membrane-based cooling system (MCS), are compared. The effect of outdoor temperature and humidity on device performance is investigated, and key insights underlying the dehumidification and cooling process are elucidated. In spite of the great potential of DCS and MCS technologies, our results underscore the need for improved system-level design and integration if DCS or MCS are to compete with VCS. Our findings have significant implications for the design and operation of next-generation HVAC technologies and shed light on potential avenues to achieve higher efficiencies in dehumidification and cooling applications.

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