Double Pipe Research Articles

Design of double pipe heat exchanger structures using linear models and smart enumeration

Design of double pipe heat exchanger structures using linear models and smart enumeration

The fluid flow and heat transfer characteristics of R-32 in a small Tube

Due to the Global Warming effect considerations, refrigerants with lower value of the Global Warming Potential will be the next generation refrigerants which are used in the air-conditioner systems. Currently, a new developed refrigerant R-32 has proposed to substitute R-410A. Therefore, many air-conditioning manufactures have determined refrigerant R-32 in their products and some studies have been discussed in recent years. However, the information of refrigerant R-32 on saturation temperature around 10°C is still insufficient, and the heat transfer coefficient (HTC) of refrigeration system around -20°C to -40°C has not been clarified. In this study, two-phase HTCs and pressure drops of refrigerant R-32 are measured in a horizontal tube with 4.0 mm inner diameter, and at saturation temperature of 10°C. The test section is a double pipe heat exchanger, where refrigerant flows in the tube side and water flows in the annular side. Also, modified Wilson Plot method was used to calculate the single-phase HTCs and pressure drops of R-32 refrigerant. In this study, two-phase experiments were conducted at vapor qualities ranging from 0.1 to 0.9 where the range of mass fluxes was 200 to 600 kg m−2 s−1 and heat fluxes ranging from 26 to 46 kW m−2. The results showed that the two-phase test results agreed well with the correlations of Shah (Shah, 1982), Gungor and Winterton (Gungor and Winterton, 1986), and Liu and Winterton (Liu and Winterton, 1991). However, the accuracy of results at different flow conditions was different, this was attributed to the change in the enhancement factor of each flow boiling model.

Evaluation for the performance of heat transfer process in a double pipe heat exchanger using nanofluids

This research investigates the effects of employing nanofluids in a tubular heat exchanger on the heat transfer process. The performance of employing water as a base fluid and multi-wall carbon nanotubes (MWCNTs) with a varying concentration nanofluid as operational fluids was investigated in an experimental investigation. The current study makes use of an Armfield Heat Exchanger (HT31) and an Armfield heat exchange service unit (HT30X). Five volumetric concentrations of nanomaterials were used to make nanofluids (0.22%, 0.33%, 0.66%, 1.1%, 1.53%). The Reynolds number of the flow inside the tube ranged from 1598 to 8000. By measuring the variables, the overall heat transfer coefficient, pressure drop, friction factor, and mean Nusselt number are computed. The overall heat transfer coefficient increases as the concentration of MWCNTS and the mass of flow increase, according to the experimental data. In comparison to distilled water, the Nusselt number value has increased by 68%, this increase is due to the nanoparticles’ volume concentration. Pressure drop values increase significantly when nanofluids are used. The friction factor increases as the volume concentration of nanoparticles increases. A relationship between Reynolds number and MWCNT volume concentration is proposed for computing the Nusselt number. An acceptable agreement may be found by comparing the results of the current investigation to the literature.

Simulation and experimental investigation of an organic phase change material-based air-cooling system for industrial applications in the hot climate

ABSTRACT This work proposes a novel cooling system of the inlet air for industrial applications in the hot climates using organic phase change material. This cooling system consists of an inductive fan, an underground heat exchanger including double pipe phase change material. A three-dimensional transient simulation was developed to predict cooling capacity (temperature drop) using the analytical solution method within the MATLAB open-source code software. A prototype of the system was designed, built and tested in laboratory conditions to validate the modeling results. The experimental setup shows an average temperature reduction of 6°C in the air-cooling system in nine working hours, which matches with the simulation results with a variance of less than 2%. Further simulations demonstrated that an industrial scale could reduce the average temperature of intake air to 10°C in 7 hours working. The offline analysis proved a significant energy conservation opportunity in power plants. This study showed that energy performance and power generation of an industrial-scale gas turbine can be improved by 1% and 1.2 MW, respectively.

Experimental Analysis of Double Pipe Heat Exchanger with V-cut Twisted Tape Inserts using PCM Dispersed Nanofluids

The performance of a double tube heat exchanger with V-cut twisted tape inserts (VCTT) and phase change material (PCM) dispersed nanofluid is investigated experimentally. The three water-based Al2O3, PCM, and Al2O3+PCM nanofluid with different concentrations (0.01-0.1% vol.) are used. The impacts of different geometric parameters, i.e., twist ratio (TR), depth ratio (DR) and width ratio (WR) of VCTT inserts on Nusselt number (Nu), friction factor (f) and entropy generation are examined. The outcomes expose that Nu and f increase as particle concentration increases and twisting ratio decreases. A higher Nu and f are generated by a higher DR or a lower WR. In all cases, the entropy generation of nanofluid is found to be lower than that of water. For all working fluids, a rise in TR, a fall in DR, and a rise in WR increases overall entropy generation.

A Novel Experimental Setup, Modelling and Static Behaviour of Cable-Supported Pipe Systems

Large spatial requirements in both onshore and offshore necessitate the investigation of the structural suitability of Cable-supported pipe system (CSPS) for transmission of fluids. This paper presents a novel experimental setup and finite element modelling of the CSPS structure. The experimental setup involves the loading of the structure using pipe clamp loading pad. Scale down models, six scenarios accounting for the effect of mid span depth-span, number of truss modules, member sections, and single and double tubes pipe sections are presented subject to cable tension, elastic and ultimate loading of the structure. The load– displacement responses of the six scenarios shows elastic responses and within limit stress until joint failure at ultimate load. Thus, the structure possesses the strength that can support its service life until loaded to the ultimate limit of the joints. The failure mode of the structure suggested the need for the cable-truss joints to be design against sudden failure. Parametric evaluation based on member section properties reveals significant deformation when the cable section is reduced compared to other member sections. The limit displacement of 64.8m span length (L) in comparison to other cable-supported structures is within L/600 - L/250, subject to check in different scenarios.

Effects of heat exchange fluid characteristics and pipe configuration on the ultimate bearing capacity of energy piles

This paper examines the ultimate bearing capacity of energy piles in sandy and clayey soils by conducting numerical modeling under different thermal loads, fluid-pipe configurations and fluid characteristics. Accordingly, U and W-shaped fluid-pipes with different diameters were simulated using ANSYS-FLUENT software, under different inlet flow rates, fluid temperatures and ground temperatures. Moreover, a semi-empirical analytical solution is proposed for predicting the outlet temperature for different pipe configurations. Then, the energy piles were modeled using ABAQUS FE-software, and the effect of temperature distribution in U, double-U and W-shaped pipes on the ultimate bearing capacity was studied, in heating/cooling conditions. Both numerical simulations and the analytical solution were validated against experimental data. Results showed that under constant flow rate, initial inlet temperature and pipe diameter, the differences between the inlet and outlet temperature of the heat exchange fluid in the U-shaped pipes was less than that obtained for the W-shaped pipes. Also, for constant inlet temperature and pipe diameter, the temperature difference decreased when the inlet flow rate increased. It was found that under constant thermal loading conditions, the changes in the ultimate bearing capacity were higher in piles with double U-shaped pipes, followed by U-shaped pipes, and lowest for W-shaped pipes.

Improvement of the Performance of an Earth to Air Heat Exchanger for Greenhouse Cooling by the Incorporation of Water Finned Tubes—A Theoretical Approach

Proper climatic conditions in greenhouses are one of the major parameters to ensure optimum crop development. The installation of heating and cooling systems are the common solution to form a proper microclimate inside the greenhouse. However, the operation of these systems is accompanied by energy consumption. Therefore, many methods and alternative systems are sought to encounter this issue. A system which has been examined as an alternative solution for full or partial cover of a greenhouse is the Earth to Air Heat Exchanger (EAHE). Up to now, many research works have concentrated on the investigation and operation of such systems. In this study, a method to enhance the efficiency of the EAHE is examined based on the simultaneous flow of water (Water assisted earth to air heat exchanger—WAEAHE) following the concept of a double pipe heat exchanger which has been widely used in other applications. Furthermore, the improvement of the systems’ efficiency is investigated via the application of fins on the internal pipe of the heat exchanger. For the purpose of the study, different case studies have been investigated in order to reach safe results conserving the parameters affecting its efficiency. The results of the theoretical analysis have shown that the application of an internal water pipe can increase the system’s efficiency sufficiently, while it is further increased with the application of fins. In fact, the application of fins can lead to an increase of the overall heat transfer coefficients varying from 36–68%. In the current study, only the energy efficiency of the system was estimated. This system needs to be further investigated to be technically and financially efficient and applicable in actual case studies.

An advanced Grid Diagram for heat exchanger network retrofit with detailed plate heat exchanger design

This paper presents a method for heat exchanger network (HEN) optimisation considering plate heat exchangers (PHEs), incorporating detailed PHEs design. The developed method starts from a mathematical model based on the Advanced Grid Diagram, which can optimise the HEN structure. The model minimises the energy consumption cost with the constraints that enable a solution thermodynamically feasible. Then comes the heat exchanger type selection part, which is provided by a graphical tool helping to identify which types of the heat exchanger are feasible. The feasible temperature range can be easily visualised to avoid the temperature violation of PHEs. This selection part integrates the area calculation and cost calculation with the detailed heat exchanger design. The method has been tested by a case study of crude oil distillation system illustrating that the application of brazed plate heat exchangers (BHEs) of CB series manufactured by Alfa Laval can save 6.6% of the investment cost for new heat exchangers compared with the retrofit plan that only shell-and-tube and double pipe heat exchangers are used.

Enhancement of Heat Transfer in a Concentric Tube Counter Flow Heat Exchanger using CuO Nanofluids

Engineers and Scientists have always tried to increase the rate of heat transfer. The most commonly used base fluids do not provide a very high rate of heat transfer. This research work aims to investigate the enhancement of heat transfer rate in a concentric type (double pipe) counter flow heat exchanger using CuO nanofluids at different volume concentrations (0.01%, 0.05% and 0.1%). The experiments conducted on nanofluids showed that, at 0.1% volume concentration of nanofluid at 2.5 LPM, the heat transfer rate, Reynolds’s number and effectiveness were increased by 16.25%, 15.52% and 2.88% respectively compared to base fluid without nano-particles. Hence it was concluded that, CuO nanofluid is having a great potential to be used as a better heat transfer fluid in heat exchangers.

Counterflow HE analysis of Cu and SiO2 nanofluids in the developing flow region

AbstractThree concentrations of 0.2, 0.6, and 1.0 vol.% Copper/25 nm and silica/22 nm nanofluids are prepared in a base liquid glycerol–water mixture of 30:70 ratio by volume (GW70). The thermophysical properties of Cu and SiO2 nanofluids are determined with a TPS500S hot disc thermal analyzer and Brookfield viscometer in the temperature range of 20–80°C. The maximum enhancement in Cu and SiO2 nanofluid viscosity (63.4%, 35.7%), thermal conductivity (100.4%, 71.3%), and density (7.5%, 1.5%) while specific heat (7.8%, 2.3%) determined for 1.0% concentration at 80°C compared to base liquid GW70. Heat transfer experiments are conducted in a short‐length double pipe heat exchanger. The flow rates resulted in the lamifnar entry length region. A maximum enhancement in the overall heat transfer coefficient (HTC; 25.0%, 19.7%) and convective HTC (46.2%, 34.8%), respectively for Cu and SiO2 nanofluids is estimated at 1.0% concentration compared to base liquid at a bulk temperature of 35°C.

Study on flow and heat transfer characteristics of Encapsulated Phase Change Material (EPCM) slurry in Double-Pipe Heat Exchanger

Microencapsulated phase change material (MPCM) slurry as a working fluid was numerically investigated for thermal energy conservation systems due to its high heat capacity associated with the PCM. A mathematical model of a double pipe heat exchanger was developed to conduct the numerical analysis based on the Eulerian-Eulerian flow model. During simulation, it was considered that MPCM slurry flows through the inside pipe of the heat exchanger, whereas high-temperature plain water flows at the annulus side of the heat exchanger. The accuracy of the model was verified with experimental data and showed a good agreement. The effect of particle concentration, Reynolds number, and particle diameter was considered to investigate the energy transport characteristics of the MPCM slurry. The results showed that particle concentration significantly affects the heat transfer performance of MPCM slurry, and it promotes pressure drop due to an increase in viscosity. The highest average heat transfer coefficient of the slurry showed at 15% volume fraction; it was also significantly affected by the particle diameter greater than 100 µm. The local heat transfer coefficient of water and MPCM slurries were compared at a Reynolds number of 6838, and PCM-based HTFs showed a higher local heat transfer coefficient. Furthermore, a ratio of h/ΔP was presented to study the energy transport performance of MPCM slurry at different particle concentrations and compared with plain water, and it was found out that 10% volume fraction showed better performance as HTF (Heat Transfer Fluid).

NANOFLUIDS HEAT TRANSFER INTENSIFICATION IN DOUBLE PIPE HEAT EXCHANGERS: REVIEW ARTICLE

In current years, the warmth switch enhancement developed with the aid of the usage of nanofluid. A nanofluid is a kind of fluid that organized by means of dispraised of nanoparticles of metal, oxides or carbides with 100 nm size that depressed in water, ethylene glycol or oil. The enhancement of warmness transfer overall performance through expending nanofluid primarily relies upon on the type of nanoparticles, kind of base fluid, form of nanoparticles, size of nanoparticles and nanoparticles attention in the base fluid. In this paper, several newly massive numbers of studied have been being provided to discover the nanofluid enhancement the warmth switch charge in several heat exchangers kinds such as double-pipe warmth exchangers, plate heat exchangers, cross-flow warmth exchangers and shell and tube warmth exchangers. In existing review article, it presents quite a few experimental and numerical research studies that investigated the impact of using nanoparticles in the single and hybrid nanofluids to acquire greater overall performance of enhancement of warmness switch in the double pipe warmness exchangers conferring to relative route of movement of fluids (Parallel flow and Counter flow) and the nature of warmth trade process. The current study showed that there is a wide use of nanofluids in double pipe heat exchangers in all dimensions. Where the comparison showed that the use of nanofluids, whether inside the inner tube or in the annular tube of the heat exchanger, will effectively lead to heat transfer, reduce the size of the heat exchanger and reduce the cost of manufacturing and materials

Structural Analysis of Floating Net Cage Bracket in Current and Wave

Aquaculture becomes an important industry and associates with many targets of sustainable development goals. As the aquaculture industries go forward offshore, the design of the floating net cage must be able to withstand extreme sea conditions. One of the vulnerable parts of floating net cage is the floater, especially at the bracket. There is load transfer in the bracket from net drag force, mooring tension, and horizontal force of the wave. Thus, this study aims to analyze the bracket under current and wave using the finite element method. Hydrodynamic force is based on the Morison formula. The numerical model was validated with the data obtained from corresponding experimental and numerical tests. On the basis, using the environmental condition in Pangandaran, Indonesia, the structure is simulated globally to obtain the deformation and tension. The simulations of the fish cage consist of single and double pipes. Then, the bracket at the floater will be analyzed locally to get the deformation and stress distribution. The maximum stress occurs at the connection between the horizontal and outer pipe of the bracket.

A comprehensive numerical study of energy efficiency analysis of a double pipe gas cooler based on second law analysis

A numerical simulation of energy efficiency in commercially available double pipe heat exchangers in the market was investigated based on the Second law of thermodynamics in this paper. The effects of CO2 mass-flow rate, water mass-flow rate, pressure, CO2 inlet temperature, and water inlet temperature of the double pipe heat exchanger were considered to evaluate the energy efficiency by analyzing entropy generation, exergy destruction, and entransy dissipation. The changes of the entropy generation, the changes of exergy destruction, and entransy dissipation are similar regardless of the operating conditions. Pressure has the most significant effect on the energy efficiency of the double pipe gas cooler compared to other operating conditions but negligible on the exergy destruction. The pressure, flow rate, and inlet temperature have completely different effects on energy efficiency depending on the region. The entropy generation and entransy dissipation at y = 0 m to y = 0.05 m (y-axis is the radial direction) decrease with increasing pressure and the opposite after that. The increase of CO2 inlet temperature at y < 0.5 m is accompanied by an increase of entropy generation, exergy destruction, and entransy dissipation but this situation disappears after y = 0.5 m. Entropy generation, exergy destruction, and CO2 and water mass-flow rate are first negatively and then positively correlated with the cut-off point at y = 0.1 m.

Assessment of Factors Affecting the Performance of a Novel Double Condenser Heat Pipe Photovoltaic-Thermal (Pv/T) System in Hot Water Mode: An Experimental Study in the Lab

Assessment of Factors Affecting the Performance of a Novel Double Condenser Heat Pipe Photovoltaic-Thermal (Pv/T) System in Hot Water Mode: An Experimental Study in the Lab

Assessment of Factors Affecting the Performance of a Novel Double Condenser Heat Pipe Photovoltaic-Thermal (Pv/T) System in Hot Water Mode: An Experimental Study in the Lab

Assessment of Factors Affecting the Performance of a Novel Double Condenser Heat Pipe Photovoltaic-Thermal (Pv/T) System in Hot Water Mode: An Experimental Study in the Lab

Thermal Performance Investigation of Double Pipe Heat Exchanger Embedded with Extended Surfaces Using Nanofluid Technique as Enhancement

Thermal Performance Investigation of Double Pipe Heat Exchanger Embedded with Extended Surfaces Using Nanofluid Technique as Enhancement

Experimental investigation of thermal potential at diesel engine exhaust and numerical simulation of heat recovery in heat exchangers

The exhaust gas from an internal combustion engine carries away about 30% of the heat of combustion. The energy available in the exit stream of many energy conversion devices goes to waste, if not utilized properly. The major technical constraint that prevents the successful implementation of waste heat recovery is due to its intermittent and time mismatched demand and availability of energy. In this regard, the present work focused on investigating the thermal potential available at the diesel engine exhaust and its utilization for various applications. In this work, experimental investigations have been performed to identify the thermal potential available at diesel engine exhaust for different load conditions. Now to recover the available thermal potential, a double pipe heat exchanger of counter flow type has been modeled in ANSYS Design Modular. The same has been numerically simulated in ANSYS workbench environment to get the outlet temperatures of hot and cold fluids. The results have been evaluated for heat exchanger, operating at engine exhaust temperature of 478 K and cold water temperature of 298 K. Simulation results shows cold outlet temperature as 435.11 K.

A CFD investigation and heat transfer augmentation of double pipe heat exchanger by employing helical baffles on shell and tube side

The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it improves the heat exchanger's performance. The CFD analysis is used in this paper to investigate the performance of double pipe heat exchangers with and without helical baffles on both shell tube sides. The 3-D CFD model was created in Solid Works, and the FloEFD software was used to analyze the conjugate heat transfer between the heat exchanger's tube and shell sides. Heat transfer characteristic like outlet temperature of shell and tube are investigated along with pressure drop on shell and tube side. Based on CFD results of double pipe heat exchanger with helical baffle on both shell side and tube side (Type 4) gives the better results than the other type of heat exchangers with an increased pressure drop than the others, results reveals that Type 4 outlet temperature of shell side is 8% higher and on tube side it is 5.5% higher, also pressure drop on shell side is 12% higher and on tube side it is 42% higher than the other types.