Impact of Manifold Design on Heat Exchanger Efficiency

1997 ◽  
Vol 119 (2) ◽  
pp. 357-362
Author(s):  
D. K. Harris ◽  
D. G. Warren ◽  
V. W. Goldschmidt
Keyword(s):  
Heat Exchanger ◽  
Internal Flow ◽  
Heating System ◽  
Operating Conditions ◽  
Baseline Design ◽  
System A ◽  
Numerical Predictions ◽  
Forced Air ◽  
And Behavior ◽  
The Impact

The impact of manifold design on single-phase heat exchanger effectiveness is studied using the NTU-Effectiveness method. Manifolds are devices that redistribute the internal flow stream of a heat exchanger from one to several passages. Two manifold types are identified: collector box and direct split designs. The particular application considered is that of a gas fired forced air heating system. A general enhancement analysis is performed which covers four different combinations of performance and objective criteria. Three cases involve increasing the heat exchanger effectiveness while constraining either the internal flow head loss, the internal mass flow rate, or their product. The other case involves reducing the required heat exchanger flow length while constraining the heat transfer rate. Familiar convection correlations are then incorporated into the enhancement analysis to predict general trends and behavior when the main tube is split into several smaller tubes. Analytical estimates of improved effectiveness are presented for three operating conditions of an actual heat exchanger which possesses a manifold. Experimental data acquired from the gas-to-gas heat exchanger are compared to numerical predictions of its performance without a manifold (baseline design). The analytical equations developed closely predict the improvement in heat exchanger effectiveness.

Development of New Heat Exchanger Design

2011 ◽  
Author(s):  
Anthony Couzinet ◽  
Daniel Pierrat ◽  
Laurent Gros ◽  
Thierry Kunc ◽  
Antoine Foata
Keyword(s):  
Heat Exchanger ◽  
Operating Conditions ◽  
Temperature Gradients ◽  
Computational Grids ◽  
Computational Time ◽  
Test Rig ◽  
Heat Exchanger Design ◽  
Numerical Predictions ◽  
Tube Banks ◽  
Heat Transfers

This study deals with a new heat exchanger design developed by DGA Essais propulseurs [inventor: A. Foata - patents 1–4] which should improve heat transfer compared with standard gas to liquid exchangers tube banks, present better compactness without weighing down the drop loss and ensure the behaviour under drastic operating conditions (1600°C and Mach 2). This new design is based on a bundle composed of nine pairs of spiral tubes which are one to one angular drifted. The predictions of the thermal performances are so fussy whatsoever by using experimental test rig or CFD computations. On one hand, the test rig doesn’t allow to fulfil the entire range of operating conditions. And yet the standard operating conditions can shade the influence of temperature gradients on the aero thermal behaviour of the spiral bundles. On the other hand, in order to obtain reliable numerical predictions of heat transfers, the spiral bundle meshing refinement is crucial to simulate accurately the flow structure and the temperature gradients close to the inner walls. Moreover, if the grooves are explicitly taken into account in the numerical model, the computational grids required will be too fine to guarantee realistic computational time. So firstly, experimental and numerical approaches are used jointly in order to show the new heat exchanger design is sustainable. Optimization of the heat exchanger will be performed in the next phase of this study.

Thermal–Hydraulic Performance Analysis of a Convergent Double Pipe Heat Exchanger

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Ahmed T. Al-Sammarraie ◽  
Kambiz Vafai
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Hydraulic Performance ◽  
Operating Conditions ◽  
Contraction Ratio ◽  
Wide Range ◽  
Prandtl Numbers ◽  
Double Pipe ◽  
The Impact ◽  
Pipe Heat

The present investigation proposes an innovative convergent double pipe heat exchanger (C-DPHE). A two-dimensional (2D) axisymmetric heat transfer model with counterflow is employed to analyze the thermal and hydraulic performance of this configuration numerically. The impact of convergence in the flow direction, using a wide range of contraction ratio (Cr), is explored. The effect of Reynolds and Prandtl numbers on the flow and heat transfer is addressed, as well. The model results were validated with available data from the literature, and an excellent agreement has been confirmed. In general, the findings of the present study indicate that increasing the contraction ratio increases heat transfer and pressure drop in the C-DPHE. Moreover, this configuration has a prominent and sustainable performance, compared to a conventional double pipe heat exchanger (DPHE), with an enhancement in heat transfer rate up to 32% and performance factor (PF) higher than one. Another appealing merit for the C-DPHE is that it is quite effective and functional at low Reynolds and high Prandtl numbers, respectively, since no high-operating pumping power is required. Further, the optimal operating conditions can be established utilizing the comprehensive information provided in this work.

Parametric Study on Ported Shroud Locations and Geometries for a Turbocharger Compressor

2019 ◽  
Author(s):  
Suheab Thamizullah ◽  
Abdul Nassar ◽  
Antonio Davis ◽  
Gaurav Giri ◽  
Leonid Moroz
Keyword(s):  
Centrifugal Compressor ◽  
Combustion Engine ◽  
Engine Performance ◽  
Operating Conditions ◽  
Entire Study ◽  
Operating Condition ◽  
Baseline Design ◽  
Operating Range ◽  
Ported Shroud ◽  
The Impact

Abstract Turbochargers are commonly used in automotive engines to increase the internal combustion engine performance during off-design operating conditions. When used, the widest operating range for the turbocharger is desired, which is limited on the compressor side by the choke condition and the surge phenomenon. The ported shroud technology is used to extend the operable working range of the compressor, by permitting flow disturbances that block the blade passage to escape and stream back through the shroud cavity to the compressor inlet. The impact of this technology, on a speed-line, at near optimal operating condition, near choke operating condition and near surge operating condition is investigated. The ported shroud (PS) self-recirculating casing treatment is widely used to delay the onset of surge by enhancing the aerodynamic stability of the turbocharger compressor. While the ported shroud design delays surge, it usually comes with a small penalty in efficiency. This research involves designing a single-stage centrifugal compressor for the given specifications, considering the application of an automotive turbocharger. The ported shroud was then introduced in the centrifugal compressor. The performance characteristics were obtained, both at the design and at off-design conditions, both with and without the ported shroud. The performance was compared at various off-design operating speed lines. The entire study, from designing the compressor to optimizing the ported shroud configuration, was performed using the commercial AxSTREAM® software platform. Parametric studies were performed to study the effect of ported shroud axial location along the blade axial length on the operating range and performance. The baseline design, without the ported shroud (P0), and the final geometry with it for all PS inlet axial locations (P1 to P5) were analysed using a commercial CFD package and the results were compared with those from the streamline solver.

scholarly journals Enhancement of Poly-Crystal PV Panels Performance by Air-to-Air Heat Exchanger Cooling System

2021 ◽  
Vol 16 ◽  
pp. 157-163
Author(s):  
Khaleel Abushgair
Keyword(s):  
Heat Exchanger ◽  
Cooling System ◽  
Ambient Air ◽  
Bottom Surface ◽  
Solar Panels ◽  
Pv System ◽  
System A ◽  
Pv Module ◽  
Back Panel ◽  
The Impact

The temperature of silicon Poly-Crystal photovoltaic (PV) solar panels has a significant impact on their efficiency emphasizing the necessity of cooling approach to be used. The current study looked at the impact of adopting a unique forced convictive air-to-air heat exchanger as a cooling approach to boost the efficiency of PV solar panels, as efficiency of silicon Poly-Crystal PV solar panels would decrease as its temperature increased. The research was carried out experimentally with both an uncooled and cooled PV system. A unique cooling system for PV panels was designed and experimentally investigated in Amman, Jordan included a heat exchanger connected to a blower that drove ambient air over the back-panel surface and a chimney to draw the cooled air outside. This cooling system would improve the PV panel's efficiency. It was found that by directing cooled air over the bottom surface of the PV module at an ideal rate of 0.01020 m3/s, the temperature of the PV module could be reduced from an average of 40 °C (without cooling) to 34 °C. As a result, the efficiency and output power of PV modules increased by roughly 2 % and 12.8 %, respectively.

The Impact of Base Metal on the Thermal-Hydraulic Performance of Metal Foam Heat Exchanger for Cooling and Dehumidification Applications

2017 ◽  
Author(s):  
Kashif Nawaz ◽  
Anthony M. Jacobi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Base Metal ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Metal Foam ◽  
Operating Conditions ◽  
Copper Metal ◽  
The Impact

In the wake of utilization of novel materials in various thermal applications open cell metal foams have received attention due to their inherent properties such as large surface area to volume ratio and higher thermal conductivity. Additionally, complex tetradecahedron structure promotes mixing and makes them a good candidate for heat transfer applications. In this paper, a relative comparison has been made between the thermal-hydraulic performance of aluminum and copper metal foam heat exchangers with the same geometry under dry and wet operating conditions. Heat exchanger consisting of round tube with annular layer of metal foam have been considered. Experiments have been conducted using a closed-loop wind tunnel to measure the heat transfer performance and pressure drop. The impact of base metal (aluminum and copper) on the heat transfer rate has been evaluated at varying air flow rates and upstream relative humidity. It has been found that due to similar geometry (flow depth, face area, pore size) both aluminum and copper foam samples have comparable pressure drop under dry conditions. However, the pressure gradient was noticeably different for two samples under wet operating conditions. An obvious difference in heat transfer rate for aluminum and copper metal foam heat exchangers was observed under both dry and wet operating conditions. The findings have been explained in terms of the impact of the thermal conductivity of base metal and condensate retention.

scholarly journals Impact of Compressor Drive System Efficiency on Air Source Heat Pump Performance for Heating Hot Water

2020 ◽  
Vol 12 (24) ◽  
pp. 10521
Author(s):  
Mariusz Szreder ◽  
Marek Miara
Keyword(s):  
Heat Pump ◽  
Air Temperature ◽  
Heating System ◽  
Operating Conditions ◽  
Drive System ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Air Source Heat Pump ◽  
Heating Capacity ◽  
The Impact

A standard Polish household with a central heating system powered by a solid fuel furnace was chosen as a case study. The modular Air Source Heat Pump (ASHP) was used to heat the hot water outside the heating season. In this article comparative studies of the impact of the compressor drive system used on the energy efficiency of the heat pump have been carried out in operating conditions. The ASHP heating capacity and coefficient of performance (COP) were determined for the outside air temperature in the range from 7 to 22 °C by heating the water in the tank to a temperature above 50 °C. For the case of a fixed speed compressor, average heating capacity in the range 2.7−3.1 kW and COP values in the range 3.2−4.6 depending on the evaporator supply air temperature were obtained. Similarly, for the inverter compressor, the average heating capacity in the range of 2.7−5.1 kW was obtained for the frequency in the range of 30–90 Hz and COP in the range 4.2−5.7, respectively. On cool days, the average heating capacity of the heat pump decreases by 12%. For the simultaneous operation of two compressors with comparable heating capacity, lower COP values were obtained by 20%.

scholarly journals Performance evaluation of a novel PVT-GSHP heating system on energy-efficient poultry houses: long-term monitoring

2020 ◽  
Author(s):  
Tugba Gurler ◽  
Theo Elmer ◽  
Yuanlong Cui ◽  
Siddig Omer ◽  
Saffa Riffat
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Heating System ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Solar Pv ◽  
Pump System ◽  
Poultry House ◽  
Poultry Houses

Abstract The case study presented in this paper is an innovative ground source heat pump (GSHP) system constituted by a hybrid Photovoltaic Thermal (PVT) solar system for poultry houses. Farmers tend to not to apply GSHPs because of the high prices of excavation and time consumption. The innovative heat pump system assessed in this study comprises of a new type of heat exchangers; a thin-tube solar polyethylene heat exchanger installed between roof tiles and PV panels and a novel vertical ground heat exchanger to utilize the heat stored in the soil. The heating system applied to a poultry house are monitored and evaluated under a variety of environmental and operating conditions to achieve annual/long-term efficiency of the heating system in Kirton, UK. The maximum heating demand of the poultry house is determined 34.4 MWh/PC while the minimum is 11,1 MWh/PC. The monitored results show that the heat pump produced 15.02 MWh of thermal energy per annum. Solar PV and heat pump worked very well together with solar PV covering all the heat pump’s annual electrical energy requirement and generated 8.74 MWh of extra electricity exported to the grid. The seasonal coefficient of performance is found 3.73 through a year. The novel PVT-GSHP heating system is a very promising solution for high fossil fuel consumption in the agriculture industry and the energy savings of the whole system can be noticeably increased dependent up on the system controlling.

scholarly journals A System-Level Modelling of Noise in Coupled Resonating MEMS Sensors

2020 ◽  
Vol 3 (1) ◽  
pp. 5
Author(s):  
Vinayak Pachkawade
Keyword(s):  
Noise Source ◽  
Operating Conditions ◽  
Sensor System ◽  
System Level ◽  
Mems Sensors ◽  
Noise Sources ◽  
System A ◽  
Sensing Applications ◽  
Mechanical Noise ◽  
The Impact

This paper presents realistic system-level modeling of effective noise sources in a coupled resonating mode-localized MEMS sensors. A governing set of differential equations are used to build a numerical model of a mechanical noise source in a coupled-resonator sensor and an effective thermo-mechanical noise is quantified through the simulation performed via SIMULINK. On a similar note, an effective noise that stems from the electronic readout used for the coupled resonating MEMS sensors is also quantified. Various noise sources in electronic readout are identified and the contribution of each is quantified. A comparison between an effective mechanical and electronic noise in a sensor system aids in identifying the dominant noise source in a sensor system. A method to optimize the system noise floor for an amplitude-based readout is presented. The proposed models present a variety of operating conditions, such as finite quality factor, varying coupled electrostatic spring strength, and operation with in-phase and out-of-phase mode. The proposed models aim to study the impact of fundamental noise processes that govern the ultimate resolution into a coupled resonating system used for various sensing applications.

scholarly journals Numerical study of the effect of gas-to-liquid ratio on the internal and external flows of effervescent atomizers

2018 ◽  
Vol 42 (4) ◽  
pp. 444-456 ◽  
Author(s):  
Milad Mousavi ◽  
Ali Dolatabadi
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Internal Flow ◽  
Operating Conditions ◽  
Liquid Ratio ◽  
Spray Cone ◽  
Numerical Predictions ◽  
Gas To Liquid ◽  
Discharge Orifice

In an effort to capture the complex evolving interface of internal and external flow in an effervescent atomizer, a compressible Eulerian method, along with the volume-of-fluid method coupled with the large eddy simulation model, are employed in a two-phase flow system. Water is injected into the atomizer with a constant mass flow rate of 0.0133 kg/s (i.e., 800 mL/min). The mass flow rate of air is adjusted to vary the gas-to-liquid ratio (GLR) from 0.55% to 2.6%. It is observed that the increase in the GLR is accompanied by an evolution of the internal flow from a complex bubbly flow to an annular flow, which consequently reduces the liquid film thickness at the discharge orifice. Further studies on the internal pressure illustrate the critical condition, which leads to choked flow and pressure oscillations at the discharge orifice. Increasing the GLR was found to affect the internal flow, resulting in changes to primary atomization parameters such as a shortening of the breakup length and a widening of the spray cone angle. The numerical predictions are in good agreement with the experimental results under the same operating conditions.

Multistage Self-Priming Pump Performance Simulation & Test Research

2014 ◽  
Vol 651-653 ◽  
pp. 780-783
Author(s):  
Gao Feng Liang ◽  
Qiang Gao
Keyword(s):  
Design Theory ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Simulation Method ◽  
Hydraulic Performance ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Pump Design ◽  
Multi Stage ◽  
The Impact

Currently the application of traditional centrifugal pump design theory to develop the multi-stage centrifugal pumps is very mature, but the factor of affecting hydraulic performance of centrifugal self-priming pump is still unclear. In this paper, using CFD method to simulate the hydraulic performance of the multistage self-priming pump in different operating conditions, and get the performance prediction curve. The simulation results were compared with experimental data, the result shows that simulation method can accurately predict the performance and internal flow characteristics of multi-stage self-priming pump. The impact on the hydraulic performance by water-keeper chamber and the gas-liquid separation chamber is very limited. The self-priming components can provide a better hydraulic performance. This will be as a reference for the design of self-priming pump.

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