Managing water on heat transfer surfaces: A critical review of techniques to modify surface wettability for applications with condensation or evaporation

As an emerging sunlight‐harvesting material, halide perovskite has obtained extensive achievements on device efficiency and stability in the past decade. Especially, the efficiency of lab‐scale perovskite solar cells (PSCs, 25.2%) is already comparable with that of crystalline silicon solar cells. However, the development of large‐scale perovskite solar modules is far behind small area devices due to difficult fabrication process and stringent requirements for film quality, the Achilles’ heel to hinder their commercialization. Therefore, the coating techniques of perovskite modules need to be developed and optimized continuously. Moreover, the underlying mechanism along with these coating processes should be revealed urgently. Herein, the recent advances for several popular coating methods are systematically summarized that are widely applied in the deposition of large‐scale films. The relevant mechanistic study, including the formation of wet film, and subsequent nucleation and growth kinetics during coating process, are discussed. The main target is to gain insight into the large‐scale PSCs fabrication. Hopefully, useful guidance is provided to further improvement of efficiency and stability of PSCs, which finally promotes their commercialization.

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Section: The Overview Of the Processes From Solution To Thin Filmmentioning

confidence: 99%

Insights into Large‐Scale Fabrication Methods in Perovskite Photovoltaics

Niu

Chen

et al. 2020

Adv Energy and Sustain Res

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“…Such conditions may occur, especially for the lower tubes (counting from the top tube rows) placed under the refrigerant distributor. Since at dry areas heat transfer happens only via natural convection, the lower liquid mass flow rates lead to the deterioration of the overall external heat transfer performance [77].…”

Section: Effect Of the Number Of Flooded Tube Rows And The Refrigeranmentioning

confidence: 99%

A General Approach in Optimization of Heat Exchangers by Bio-Inspired Artificial Intelligence Methods

Krzywański

2019

Energies

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The paper introduces the artificial intelligence (AI) approach as a general method for the design and optimization study of heat exchangers. Genetic Algorithms (GA) and Artificial Neural Networks (ANN) are applied in the paper. An AGENN model, combining Genetic Algorithms with Artificial Neural Networks, was developed and validated against the desired data on a large falling film evaporator. A broad range of operating conditions and geometric configurations are considered in the study. Four kinds of tubes are deliberated, including plain and enhanced tubes. Different tube pass arrangements, i.e., top-to-bottom, bottom-to-top, and side-by-side, are discussed. Finally, the effects of liquid refrigerant mass flow rate, as well as the number of flooded tubes on the performance of the evaporator, are analyzed. The total heat transfer rate of the evaporator, predicted by the model, is in good agreement with the desired data; the maximum error is lower than ±3%. The highest heat transfer rate of the evaporator is 1140.01 kW and corresponds to Turbo EHP tubes, and bottom-to-top tubes pass arrangements, which guarantee the best thermal energy conversion. The presented approach can be referred to as a complementary technique in heat exchanger design procedures, besides the common rating and sizing tasks. It is an effective and alternative method for the existing approaches, considering the complexity of analytical and numerical techniques as well as the high costs of experiments.Construction features of the direct-transfer-type heat exchangers are the base of their classification, according to the geometry of construction criterion. Considerable flexibility in heat exchangers design can be observed for tubular ones where tube diameter, the number of tubes, the tube length, the pitch of the tubes, and the tube arrangement can be easily modified. Tubular heat exchangers can be classified into double-pipe, shell-and-tube and spiral-tube-type heat exchangers as heat transfer coefficients in a spiral tube are higher than those in a straight one. Plate heat exchangers are built of thin plates (plain, wavy, or corrugated) forming flow channels and can be categorized into: gasketed plate (consists of a series of thin plates with corrugation or wavy surfaces that separate the fluids), spiral plate (formed by rolling two long, parallel plates into a spiral), and lamella (Ramen) type of heat exchanger (a set of parallel, thin plate channels or lamellae (flat tubes or rectangular channels) placed longitudinally in a shell) [2].Extended surface heat exchangers contain fins or appendages on primary heat transfer surfaces to increase the heat transfer area (usually on the gas side).According to the heat transfer mechanisms criterion, there can be distinguished: 1. single-phase convection on both sides, 2. single-phase convection on one side and two-phase convection on other side, 3. two-phase convection on both sides.Finally, according to the flow arrangements criterion, the following fluid-flow path through the heat exchanger can exist:...

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“…Ferrofluids have superior properties which includes variable viscosity, improved thermal conductivity and formation of spike like structure in the presence of an external magnetic field [6,8]. Addition of ferro particles or nano particles into cooling water of IC Engines increases the heat transfer which results in the size reduction of heat exchanger [9]. This will facilitate reduction of size of overall weight of the engine, which will reduce the fuel consumption.…”

Section: Introductionmentioning

confidence: 99%

CFD simulation for evaluation of optimum heat transfer rate in a heat exchanger of an internal combustion engine

Kocheril

Elias

2020

Int. J. Simul. Multidisci. Des. Optim.

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Heat exchanger is an essential component of an engine cooling system. Radiators are compact heat exchangers used to transfer the heat absorbed from engine to the cooling media. The jacket cooling water gets cooled and re-circulated into system after exchanging the heat with cooling water in a heat exchanger. Conventional fluids like water, oil, ethylene glycol, etc. possess less heat transfer performance; therefore, it is essential to have a compact and effective heat transfer system to obtain the required heat transfer. A reduction in energy consumption is possible by improving the performance of heat exchanging systems and incorporating various heat transfer enhancement techniques. In this paper, the heat transfer rate using nano-sized ferrofluid with and without magnetization is analysed using CFD simulation and compared with the experimental values obtained from a heat exchanger using water as base fluid. The heat transfer rate is measured using different combinations by varying the percentage of nano particles and by introduction of different magnetic intensity (gauss) on to the ferrofluid. The optimum heat transfer rate and efficiency of heat exchanger is calculated with the different combinations and the values are compared with the values of CFD simulation. CFD simulation was undertaken for water alone as cooling media and for water with ferro particle addition from 2% to 5%. The difference in temperature observed to be similar with experimental values. The deviation is within the acceptable limit and therefore the experimental findings are validated. The experiment was conducted on a parallel flow heat exchanger with water alone as cooling media, water with varying percentage of ferro fluid and water with varying magnetic intensity on ferrofluid. Percentage of ferro particles added up to where the optimum temperature difference could be obtained and the magnetic intensity also varied up to the optimum value.

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Managing water on heat transfer surfaces: A critical review of techniques to modify surface wettability for applications with condensation or evaporation

Cited by 106 publications

References 203 publications

Insights into Large‐Scale Fabrication Methods in Perovskite Photovoltaics

Insights into Large‐Scale Fabrication Methods in Perovskite Photovoltaics

A General Approach in Optimization of Heat Exchangers by Bio-Inspired Artificial Intelligence Methods

CFD simulation for evaluation of optimum heat transfer rate in a heat exchanger of an internal combustion engine

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