Inlet Water Flow Research Articles

Thermochemical heat storage and material behavior of calcium hydroxide fine powder in a fluidized bed reactor

The Ca(OH)2/CaO reaction has attracted much attention in thermochemical heat storage. However, commercial Ca(OH)2 is usually offered as a fine powder that tends to agglomerate in the fluidized bed and affects heat storage performance. The experimental study on these issues is incomplete. In this paper, a fluidized bed thermochemical heat storage test system is built to study the heat storage and release process of Ca(OH)2 fine powder. The experimental results indicate that the water vapor is the primary factor in agglomeration. The increase in heat storage temperature, fluidization velocity, and inlet water flow rate can all reduce reaction time. However, the effect of heat storage temperature on agglomeration is negligible. While a high fluidization velocity can alleviate the agglomeration, a high inlet water flow rate intensifies the agglomeration. The heat storage density decreases by about 12 % after 5 cycles owing to the material loss, while the agglomeration is trending upward. The specific surface area and specific pore volume decrease by 46.59 %, and 13.89 % respectively, which slows down the heat storage process. This work can serve as a reference for alleviating the agglomeration, as well as the operation and adjustment of the fluidized bed.

The influence of operating parameters on the performance of PEMWE electrolytic cell

Proton exchange membrane (PEM) is considered the most promising green hydrogen production technology in the future. The proton exchange membrane electrolysis cell (PEMEC) involves a complex process of multiple physical fields, including charge transfer, gas transfer, and heat transfer, during operation. Increasing the inlet water flow rate within a certain range is beneficial for increasing the output performance of the electrolysis cell and can also reduce the average temperature of the proton exchange membrane. But when the inlet flow rate increases to a certain amount, it has no effect. As the electrolysis voltage increases, the electrochemical performance of the electrolysis cell also increases, and the temperature of the proton exchange membrane and the current density of the catalytic layer also increase with the increase of voltage.

Novel optimal high pressure determination method for CO2 air source heat pump water heater: Experimental study and methodology development

As an efficient and environment-friendly solution to replace traditional fuel-fired boiler, CO2 air source heat pump water heater (HPWH) is widely used in the commercial and residential water heating. In order to achieve the optimal performance of CO2 air source HPWH systems, the effects of electronic expansion valve (EEV) opening and inlet water flow rate on system performance are experimentally studied and the optimal matching of the two parameters are obtained in this study. Then, the relationship between the optimal high pressure and the optimal matching of EEV opening and water flow rate is discussed. Finally, a new parameter, the endpoint temperature difference (ΔTep), is defined and a novel control strategy of ΔTep = 0 is proposed to determine the optimal high pressure. The results indicate that the optimal matching of EEV opening and water flow rate corresponds to the optimal high pressure and the best COPheat of system. A smaller ΔTep corresponding to a better matching degree and a larger system COPheat. The maximum deviation between the high pressure determined by the proposed new control strategy and the optimal high pressure is less than 1.8 %, and the system COPheat under the proposed new control strategy can achieve more than 97.6 % of the maximum COPheat. Therefore, the proposed control strategy in the paper is better than that of the commonly used off-line optimal high pressure correlation and can provide guidance for the efficient operation of the CO2 air source HPWH system.

In Situ Conductive Heating for Thermal Desorption of Volatile Organic-Contaminated Soil Based on Solar Energy

A novel conductive heating method using solar energy for soil remediation was introduced in this work. Contaminated industrial heritage sites will affect the sustainable development of the local ecological environment and the surrounding air environment, and frequent exposure will have a negative impact on human health. Soil thermal desorption is an effective means to repair contaminated soil, but thermal desorption is accompanied by a large amount of energy consumption and secondary pollution. Therefore, a trough solar heat collection desorption system (TSHCDS) is proposed, which is applied to soil thermal desorption technology. The effects of different water inlet temperature, water inlet velocity and soil porosity on the evolution of soil temperature field were discussed. The temperature field of contaminated soil can be numerically simulated, and a small experimental platform is built to verify the accuracy of the numerical model for simulation research. It is concluded that the heating effect is the best when the water entry temperature is the highest, at 70 °C, and the temperature of test point 4 is increased by 50.71% and 1.42%, respectively. When the inlet water flow rate is increased from 0.1 m/s to 0.2 m/s, the heating effect is significantly improved; when the inlet water flow rate is increased from 0.5 m/s to 1.5 m/s, the heating effect is not significantly improved. Therefore, when the flow rate is greater than a certain value, the heating effect is not significantly improved. The simulation analysis of soil with different porosity shows that larger porosity will affect the thermal diffusivity, which will make the heat transfer effect worse and reduce the heating effect. The effects of soil temperature distribution on the removal of petroleum hydrocarbon C6–C9 and trichloroethylene (TCE) were studied. The results showed that in the thermal desorption process of petroleum hydrocarbon C6–C9-contaminated soil, the removal rate of pollutants increased significantly when the average soil temperature reached 80 °C. In the thermal desorption of trichloroethylene-contaminated soil, when the thermal desorption begins, the soil temperature rises rapidly and reaches the target temperature, and a large number of pollutants are removed. At the end of thermal desorption, the removal of both types of pollutants reached the target repair value. This study provides a new feasible method for soil thermal desorption.

Preparation of dodecahydrate disodium hydrogen phosphate shape-stabilized composite phase change materials and their experimental investigation in solar thermal storage and exothermic systems

To alleviate the mismatch between energy supply and demand caused by the spatial and temporal distribution mismatch and weather uncertainty during solar energy utilization, solar energy is combined with phase change thermal storage technology to improve the performance of solar thermal storage systems. In this study, a shape-stabilized composite phase change material with a highly absorbent resin structure is proposed as thermal storage material. This material exhibits a latent heat of phase change of 246.5 J/g, a thermal conductivity of 1.968 W/(m·K), and maintains good stability after 200 thermal cycles. Subsequently, a detachable experimental setup integrating solar energy with a phase change thermal storage tank was designed and constructed. The effects of inlet and outlet hot water flow rates and heat source temperature on heat storage time and the amount of stored water were investigated separately. The experiments show that increasing the heat source temperature during storage effectively shortens the storage time, and that the largest effective amount of hot water is obtained when the exothermic flow rate is 300 L/h. The study's results are significant for broadening solar energy utilization, alleviating the mismatch between solar energy supply and demand, and evaluating the thermal performance of latent heat storage systems.

Optimizing efficiency of proton exchange membrane electrolyzer system based on multiphysics model and differential evolution strategy

This work focuses on a comprehensive performance enhancement considering hydrogen production, energy consumption of balance of plant (BOP), and thermal safety by optimizing the inlet water temperature and flow velocity. First, a multiphysics model is introduced to show that the inlet water temperature and flow velocity can affect the current density as well as the hydrogen production. An overall efficiency is defined to balance the hydrogen production and the energy consumption of BOP. After that, a surrogate model is established based on artificial neural network to replace the multiphysics model because of its huge computational effort. For the thermal safety and performance enhancement, an optimization problem with the maximum membrane temperature as a constraint and the overall efficiency as an objective function is proposed. The differential evolution (DE) strategy with the feasibility rule (FR) is adopted to solve this optimization problem. Finally, the DE-FR-based optimization algorithm is applied to three typical days in Chengdu of China representing summer, winter, and transitional seasons, respectively. Compared to the invariant inlet water flow velocity and temperature, the optimal and time-varying parameters improve their efficiency by relative percentages of 2.68%, 3.79%, and 3.29% for the three typical days, respectively.

Comparative Study on Heat Dissipation Performance of Pure Immersion and Immersion Jet Liquid Cooling System for Single Server

Heat dissipation has emerged as a critical challenge in server cooling due to the escalating number of servers within data centers. The potential of immersion jet technology to be applied in large-scale data center server operations remains unexplored. This paper introduces an innovative immersion jet liquid cooling system. The primary objective is to investigate the synergistic integration of immersion liquid cooling and jet cooling to enhance the heat dissipation capacity of server liquid cooling systems. By constructing a single-server liquid cooling test bench, this study compares the heat dissipation efficiencies of pure immersion and immersion jet liquid cooling systems and examines the impact of inlet water temperature, jet distance, and inlet water flow rate on system performance. The experimental outcomes show that the steady-state surface heat transfer coefficient of the immersion jet liquid cooling system is 2.6 times that of the pure immersion system, with increases of approximately 475.9 W/(m2·K) and 1745.0 W/(m2·K) upon adjustment of the jet distance and flow rate, respectively. Furthermore, the system model is streamlined through dimensional analysis, yielding a dimensionless relationship that encompasses parameters such as inlet water temperature, jet distance, and inlet water velocity. The correlation error is maintained below 18%, thereby enhancing the comprehension of the immersion jet cooling mechanism.

Carbon dioxide stripping from acidic wastewater through a vortex venturi tubular microbubble generator

Microbubble generation technology can improve CO2 stripping efficiency while consuming less sweeping gas. In this paper, a vortex venturi tubular microbubble generator is developed based on the concept of “Initial bubble generation with a thin plate type static mixing element” and “Bubble collapse with a venturi channel”. Microbubble characteristics were tested, followed by post-processing of the focused beam reflectance measurement (FBRM) to obtain a multidimensional dataset. The test results indicated that the microbubble quality generated by the vortex venturi tubular microbubble generator was higher than that of the SV-type static mixer. When the gas-liquid volume ratio was 1, the average bubble diameter was 107.05 μm, and microbubbles accounted for 93.29 %. The average bubble diameter of the SV-type static mixer was 473.55 μm, and the proportion of microbubbles was 23.81 % under identical conditions. Furthermore, the CO2 removal efficiency and pH enhancement rate were greatly affected by the gas-liquid volume ratio and the inlet water flow rate, and both fitted an exponential equation correlation. Accordingly, when the gas-liquid volume ratio increased, the quantity of bubbles generated significantly influenced the CO2 stripping efficiency. The stripping efficiency based on the tubular microbubble generator is significantly higher than that of the SV-type static mixer. When the gas-liquid volume ratio was 1, the CO2 removal efficiency was equivalent to that of the SV-type static mixer at a gas-liquid volume ratio of 3.5. When achieving equal CO2 removal efficiency, the gaseous nitrogen consumption of the tubular microbubble generator was 48.61 %-63.30 % lower than that of the SV-type static mixer, and the corresponding energy consumption of the gas compressor was reduced by 38.24 %-55.83 %. The CO2 stripping process based on the vortex venturi tubular microbubble generator offers an environmentally and economically viable treatment option for acid wastewater.

Experiments and modeling of solid oxide co-electrolysis: Occurrence of CO2 electrolysis and safe operating conditions

Solid Oxide Electrolysis Cell (SOEC) has attracted considerable attention for its potential scalability and high energy conversion efficiency. It is capable of electrolyzing both H2O and CO2 simultaneously, generating syngas that can be further synthesized into carbon-based fuels, which are good energy carriers for long-term energy storage. However, despite its promise, the understanding of the reaction mechanism crucial for extending cell longevity remains incomplete, and concerns persist regarding carbon deposition during co-electrolysis. A dual approach, combining experiments and Multiphysics simulations was adopted to explore the reaction mechanism and carbon deposition risk across a wide range of operating conditions on industrial-size cells. Both experimental observations and simulation results indicate that CO2 electrolysis and carbon deposition are significantly influenced by the inlet water content and flow rates at the fuel electrode. Increasing the inlet H2O concentration and fuel electrode flow rates lead to CO2 electrolysis occurring at higher current densities. Also, carbon deposition, which was found at the interface of fuel electrode and electrolyte, can be mitigated by controlling the conversion rate relative to the inlet H2O content and by increasing the flow rate at the fuel electrode. Additionally, the current density distribution of H2O electrolysis and CO2 electrolysis across the cell were also investigated. The obtained insights hold significance for the practical operation of SOEC co-electrolysis.

Theoretical modeling of process heat transfer mechanism in U-shaped molten salt heat exchanger

U-shaped tube molten salt heat exchanger (MSHE) plays an important role for further improving peak shaving capacity of coal-fired unit (CFU) coupled extraction thermal storage system (ETSS). Nevertheless, existing experimental approach cannot reveal process heat transfer characteristics (HTCs) of MSHE. Meanwhile, investigation exploring factors restricting heat transfer enhancement for MSHE in theory is still vacant. In this paper, a theoretical method for MSHE was developed to determine process mechanism of heat transfer to capture perspective of enhanced heat transfer. Heat transfer performance of U-tube MSHE was theoretically unpacked. Deliberating work was executed with inlet water flow rate of 69–139 kg/s, water temperature of 120–170 °C, salt flow rate of 28–58 kg/s and salt temperature of 350–400 °C. Whereupon, the process mechanism of heat transfer inside MSHE was obtained with redeeming lack of theoretical exploration.Research shows, total HTC respectively increases by 2.57 and 1.88 W/(m2·°C) with 10 °C increasing of molten salt inlet temperature (MSIT) and 14 kg/s ascension in condensate flow rate (CFR). It is signified thermal resistance of countercurrent section of MSHE mainly involving HTCs of MSHE with increment of MSIT and CFR. Such privileged sites are main factor restricting heat transfer enhancement. Moreover, total HTC respectively increases by 2.1 and 21.84 W/(m2·°C) with 10 °C upgrading in condensate inlet temperature (CIT) and 6 kg/s increment in molten salt flow rate (MSFR). Contrary to augmenting MSIT and CFR, HTCs changing of MSHE with CIT alteration and MSFR preferment mainly attributed to downstream section and inlet position of MSHE. Meanwhile, it is discovered significant impact is generated for HTCs of MSHE with specific heat changing in molten salt. Furthermore, it was proven that Bell method is suitable for calculating HTC of molten salt on shell side in U-shaped tube MSHE. The research contents in present work can provide reliable basis for optimal design and application of U-tube MSHE in CFU.

Numerical investigations on electrolytic performance of proton exchange membrane electrolysis cell with parallel flow field

In this study, a three-dimensional simulation model of PEMEC with parallel flow field was established, the heat and mass transfer, electrochemical reactions were described to investigate the electrolytic performance. The distribution characteristics of temperature, liquid water and gas products in the electrolysis cell were obtained. The results show that during the operation of PEMEC system, the liquid water content decreases sequentially along the flow channel direction, while there is a significant temperature gradient in the flow direction of the electrolysis cell. The increase of the initial temperature can increase the current density of the electrolytic cell when the temperature increases from 60 ℃ to 80 ℃, the current density can be increases by 7.86 %, but it can also lead to the dehydration of PEMEC, resulting in thermal degradation of PEMEC, and further the reactivity and proton transfer performance were decreased. It is also found that the increase of liquid water inlet flow not only increased the reactant concentration, accelerated the chemical reaction rate, but also took away more heat generated by ohmic polarization as a coolant, which was conducive to the improvement of electrolytic performance. As the inlet flow rate increased from 1 mL/s to 3 mL/s, the current density at 2.4 V and 1.4 V can be increased by 3.66 % and 1.77 %, respectively, and the maximum temperature can be reduced by 7.4 K.

Enhancing PEMEC Efficiency: A synergistic approach using CFD analysis and Machine learning for performance optimization

The proton exchange membrane electrolytic cell (PEMEC) is a clean, pollution-free, and promising device for producing hydrogen from water electrolysis. This paper enhances the electrochemical performance of the PEMEC by developing a comprehensive three-dimensional two-phase non-isothermal heat and mass transfer cell model. An analysis was conducted to study the influence of various operating parameters on the temperature safety and efficiency of the cell. The performance of the latter was optimized by adopting the machine learning technology, which aimed at identifying optimal conditions for improved performance. The obtained results showed that, when the inlet water flow rate and membrane thickness were increased, the average temperature of the anode catalyst layer (A-CL) was decreased by 1.4 K and 2.31 K, respectively. This allowed to improve the safety of the electrolytic cell. However, it would reduce the hydrogen and oxygen mole fraction in the electrolyzer. On the contrary, enhancing the porosity or thickness of the anode gas diffusion layer can increase the average A-CL temperature and decrease the oxygen and hydrogen mole fraction. Therefore, the backpropagation neural network and non-dominated sorting genetic algorithm were used to predict and optimize the performance of the electrolyzer, in order to maximize its temperature safety, electrochemical reaction rate, and hydrogen evolution efficiency as much as possible. The results of this study provide a theoretical foundation for the selection of suitable cell models according to different conditions in engineering applications. It also has an application value in energy saving and sustainable development.

A real-time simulation model of water quality with the impact of internal pollution for water source reservoir.

The water source reservoirs are the important urban water source in northern China. Although external pollution has been greatly improved, the internal pollutants in reservoirs continue to accumulate with the complex deposition and release processes, resulting in potential risks to water supply safety. To address the aforementioned issue, this paper proposed a simulation model of water quality named ECOlab EU1-WSR to simulate the spatio-temporal changes of water quality under the influence of internal pollution for the water source reservoirs. Based on the analysis of the water quality characteristics and the distribution of benthic vegetation in the reservoir, a three-dimensional hydrodynamic model was established based on MIKE3, the corresponding parameters and the related state variables were set, the ECOlab EU1-WSR model was established by secondly developing the original ECOlab EU1 template, and the real-time dynamic outputs of pollutant content in sediment were added to link the water quality index with sediment nutrition index for better revealing the impact of the internal pollution on the water quality. The performance of the model was evaluated by the case application on the water quality simulation of Daye reservoir and the optimization of the connection project between Daye reservoir and Xueye reservoir in Shandong Province China. The results showed that the model can accurately and simultaneously simulate the pollution in water and sediment by the comparative verification of hydrodynamics, water temperature, and water quality. Moreover, the model can effectively reflect the influence of the accumulation, deposition, and release of internal pollution on water quality by analyzing the correlation between the content of various pollution in water body and those in sediment, such as the total nitrogen and total phosphorus in the water body at the bottom of the water intake, were negatively correlated with the total nitrogen and total phosphorus in the sediments with correlation coefficients of 0.538 and 0.917, respectively. In addition, the optimal water inlet position and water flow rate of the connection project can be optimized and determined by using the model to effectively control water quality. The established model will be a useful tool for the design and management of a reservoir, the interconnection projects, and other water bodies by adaptively recoded.

Thermal performance of solar flat plate collector using energy storage phase change materials

AbstractThe present study has been carried out to improve the overall efficiency of a conventional flat plate solar collector (FPSC) using two different heat storage phase change materials (PCMs). Two grades of paraffin wax—Paraffin‐P116 (PCM‐1) and Paraffin‐5838 (PCM‐2) as PCM are selected for the analysis based on their high heat fusion rate, low thermal conductivity, and suitable phase transition temperature. The present code has been validated with experimental results and it showed a maximum error of 6.43% in predicting the water outlet temperature. Absorber plate temperature, useful heat transfer rate, water outlet temperature and efficiencies are estimated to improve the performance of FPSC with and without PCM for various flow rates (15 lph and 30 lph) with two different weights of PCM (9 kg and 14 kg) for three different locations in India, [Chennai (13.0827° N, 80.2707° E), Bengaluru (12.9716° N, 77.5946° E), and Delhi (28.7041° N, 77.1025° E)]. The maximum increment in the efficiency of FPSC with the use of PCM‐1 is 19.59% and with the use of PCM‐2 is 16.53%. Using 14 kg of PCM‐1 with the conventional FPSC at water inlet flow rate of 15 lph increases the overall thermal efficiency up to 19.59% compared with conventional FPSC. The maximum increase in the percentage of efficiency with PCM‐1 from conventional FPSC for different cases of 15 lph‐09 kg is 16.34%, 15 lph‐14 kg is 19.59%, 30 lph‐09 kg is 14.57% and 30 lph‐14 kg is 18.45%. From the present study, it can be concluded that the overall efficiency of FPSC is increased with the use of 14 kg of PCM‐1 with conventional FPSC at the inlet water flow rate of 15 lph.

Optimized design of smart toilet spray bar flow channel based on CFD

Currently, there are significant issues with the intelligent toilets available on the market, such as a large swing of the spray bar when spraying water column and eccentricity. This paper presents four optimization schemes for the intelligent toilet spray bar channel by analysing and redesigning a specific model. Computational Fluid Dynamics (CFD) technology was employed to analyse the water flow conditions inside the spray bar of the intelligent toilet. The calculation results indicate that for the same water inlet flow rate, the optimal structure in optimization scheme 1 is the block with a length (L) of 1.5 mm. In optimization scheme 2, the optimal structure is the block located at position (3). In optimization scheme 3, the optimal structure is a 15° rotation, which exhibits the least swirls and pressure loss while maintaining the prototype structure. When the prototype structure is modified, the optimal structure in optimization scheme 4 is the excision bend pipe. This structure exhibits the lowest swirl number and pressure loss among all the optimization schemes. The determined structure offers valuable insights for enhancing the flow characteristics of the improved product.

Pollution simulation of heavy metal in saturated porous media using CFD

Visualizing contaminant transport can play a significant role in better understanding the fate of contaminants in soil. The present study aimed to evaluate contamination of aluminium and mercury in the soil through the use of computational fluid dynamics (CFD) to obtain an estimate of degraded zones. A leak from a generic stabilization pond measuring 40 m (length) and 20 m (width) was developed for the simulations. The simulations were carried out for a period of 10 years with different leak speeds, water inlet flow rates and different values of aluminum and mercury volume fractions. All governing equations was solved with the transient mode. The flow characterized as laminar, and the multiphase model was employed through the Mixture method. The time required for contamination to reach its maximum value was directly influenced by the change in speed values. The concentration of the pollutant increases as the water inlet and leakage speeds increase, however, it reduces the time needed to reach the highest pollutant value, indicating that the degree of pollution of the porous medium was greater. The study shows that contamination can be seen as a potential contaminant source for groundwater.

Investigation into the hydrogen production performance of a novel 5-kW hybrid-system composed of a solar steam generator directly connected with conventional solid oxide electrolysis cells

Coupling solar energy with solid oxide electrolysis cell has the potential to reduce electricity consumption and improve energy conversion efficiency. This study introduces a pioneering 5 kW direct-connected hybrid system that couples a solar steam generator with solid oxide electrolysis cells utilizing conventional electrical energy for the electrolysis process. The successful demonstration of hydrogen production showcases promising results. When the solar irradiation power is 2.26 kW, the inlet water flow rate is 1.23 kg/h under operations at 700 °C, the hydrogen production efficiency of the system reaches 95.2 %, and the steam conversion ratio approaches 92 %, giving a cumulative hydrogen production yield of 5,840 NL in 6.3 h. The solid oxide electrolysis system is further tested under different operating conditions of the stack and solar irradiation. The experimental results show that a greater operating temperature is conducive to more efficient hydrogen production, while more water vapor at the cathode leads to a larger steam conversion ratio. The results indicate that increasing the irradiation power is beneficial to hydrogen production while decreasing the irradiation power will lead to fluctuations of hydrogen yield. In addition, the system efficiency (45.3 %) is higher than that of a photovoltaic alkaline water electrolysis (12.6 %) or photovoltaic proton exchange membrane electrolysis (14.76 %) system at the same irradiation power. Under the same electrolysis power and cathode inlet temperature, the total power consumption of a traditional solid oxide electrolysis system is significantly greater than that of the proposed hybrid system. The comparison shows that the saved electricity of the proposed hybrid system can account for about 30 %. Therefore, the proposed hybrid system has significant efficiency and power savings advantages.

Investigation of effect of cooling water characteristics on flue gas condensation along vertical tube heat exchanger

Flue gas condensing heat exchangers obtain the highest thermal efficiency of power boilers through the recovery of sensible and latent heat of condensation from flue gases containing certain amount of water vapor. Many parameters influence the operation of economizers, among them the amount of water vapor in the flue gas and cooling water parameters. This paper presents experimental results obtained for various local parameters of vertical tube bundle economizer when the flue gas water vapor mass fraction is 6 % and 14 % and when different cooling water inlet flow rates and temperatures are applied. The results showed that the change in the water flow rate had negligible effect on variation of the local flue gas and cooling water temperature along heat exchanger. However, its effect on the condensate flux and the local Nusselt number was significant. The cooling water temperature and, especially, water vapor mass fraction had a great impact on the average Nu number, but the effect of the flue gas Re number was less evident. It was determined that there exists a ratio of cooling water to flue gas mass flow rate, where the operation of the economizer is optimal in terms heat transfer and condensation efficiency.

Experimental study of the influence of pad angle on the thermal performance of a direct evaporative cooling system

One of the most important parts of direct evaporative cooling systems is the cooling pad. Pads vary in materials and construction features. The parameters studied in the performance of the pads are air speed, pad thickness, geometrical characteristics, and its configuration and the provided water flow rate. The performance of the pads is usually determined through saturation efficiency, pressure drop, temperature drop and humidity increase in the treated air, evaporation and water consumption, cooling capacity, coefficient of performance, and heat and mass transfer coefficients. Since the geometry and how to place the pad in the evaporative cooling system is one of the most important issues related to the performance of such systems, the present work experimentally investigates the amount of cooling and evaporation of the direct evaporative cooling system under 5 different angles of placement of the cellulose pad in relation to the vertical position. It includes angles of 0^circ, 5^circ, 10^circ, 15^circ, and 20^circ in 5 different air speeds, 2 different inlet water flow rates, 2 inlet air temperatures, and 2 different inlet water temperatures. Results show that the lowest output temperature, highest air relative humidity, highest coefficient of performance (about 12% more than 0^circ), highest saturation efficiency, and highest evaporation rate are obtained in the case of a 15^circ of cooling pad placement angle.

Study on the influence characteristics of thermal effect of internally cooled dehumidifier

In order to investigate the dehumidification strengthening effect of multichannel flat tube thermal effect and analyze its strengthening mechanism, a corrugated fins-multichannel flat tube based internally cooled dehumidifier structure is designed. The optimum dehumidifier flow type was determined and the dehumidification strengthening characteristics and thermal mechanism of the multichannel flat tube under different air and cold source conditions were experimentally analyzed. The results showed that the flow type B2 (air–solution countercurrent and water–solution countercurrent) had the best dehumidification performance. High-temperature and high-humidity environments can worsen the dehumidification strengthening effect of the multichannel flat tube and the effective utilization of cooling power, although high humidity has a stronger inhibitory effect, its inhibition mechanism is different. When the inlet air humidity is 25.8 g/kg, the dehumidification performance increases by up to 16.6%; Decreasing the inlet water temperature and increasing the inlet water flow significantly improved the dehumidification strengthening effect of the multichannel flat tube. Furthermore, the multichannel flat tube can eliminate 100% of total heat when the inlet water temperature is below 20.7 °C.