System Coefficient Of Performance Research Articles

Investigation of the integrated fuel cell, battery, and heat pump energy systems

The integration of an advanced fuel cell battery electric vehicle was proposed to extend the driving range, increase the overall energy efficiency, and produce an additional cabin space heating service for on-board vehicle application in winter. The adopted heat pump absorbs heat from the fuel cell and battery during charging and discharging scenarios at the heat pump's cold end and transfers it to the cabin supply air for cabin heating. A numerical model for the proposed system was developed and validated by published experimental results. A comprehensive evaluation of the influence of fuel cell output current, battery discharging rate, ambient air temperature, evaporator coolant inlet temperature and refrigerant subcooling degree on the Coefficient of Performance (COP), outlet air temperature, and Equivalent Effective Battery Capacity (EEBC) were conducted. In addition, in this study, a detailed comparison of proposed system to previously published existing systems was carried out in terms of COP, heating capacity, EEBC, and operating price in order to examine the advantages of the proposed system. Results showed that the proposed system was not sensitive to ambient air temperature, but evaporator coolant inlet temperature had the greatest impact on COP, compared to other defined independent variables. A maximum COP of 6.07 could be observed when the evaporator coolant inlet temperature was 32 °C. Although increasing fuel cell output current and battery discharging rate could increase heating capacity, it would decrease outlet air temperature as well. The price of a single charging cycle for running for a 4-hour period was estimated. Compared to conventional Electric Vehicle Air Source Heat Pump (EVASHP) system and Positive Temperature Coefficient (PTC) heaters, the proposed system has the lowest cost which was £10.40per charging cycle while the others are £13.8 and £19.2 respectively when providing the same EEBC and heating capacity. Additionally, the payback period was 10,500 charging cycles. Overall, this study provides a potential solution for efficient cabin heating of electric vehicles in extremely cold weather with twice the EEBC of the existing EVASHP system and with 2.8 times of a PTC system both at −20 °C and the operating price is also 1/3 lower than the existing EVASHP. Meanwhile, the COP of the proposed system is 2.3 times that of the existing systems. It can sufficiently increase the driving range of electrical vehicles in winter and eliminate driving range anxiety.

Numerical analysis of the effect of the evaporator inlet-outlet position on the PV-T performance

The increase in global energy consumption and carbon dioxide emissions increase the interest in renewable energy sources. Solar energy is at the forefront of renewable energy sources, and the decrease in cell efficiency due to various reasons during operation is an obstacle to this technology. Increasing the temperature of photovoltaic cells during operation causes a decrease in cell efficiency. Control of photovoltaic cells temperature is crucial in terms of both prolonging the economic life of the cells and increasing the efficiency of the system. The effect of the evaporator inlet and outlet position of the fluid on the heat transfer is known, but this effect was not examined in the studies carried out to increase the efficiency of the PV-T (photovoltaic–thermal) system. In the current study, the system efficiency parameters and COP (coefficient of performance) values of a PV-T evaporator cooled by forced air circulation were investigated by CFD (computational fluid dynamics) analysis. The analyzes were carried out in a single array for three different flow rates (0.0125 kg/s, 0.0250 kg/s, 0.0500 kg/s) and nine different evaporator inlet-outlet positions (CC, CL, CR, RC, RL, RR, LC, LL, LR), constant radiation of 1000 W/m^2. It was determined that there is a total efficiency difference of over 20% and an overall COP difference of over 25% between the best and worst inlet-outlet positions. The highest total and thermal efficiency were obtained for the RR condition, and the highest electrical efficiency was obtained for the LR condition but in the long-term, the highest efficiency can be achieved with the LC design. In the study also the highest COP values were calculated for the CL condition and the worst COP values for the RR condition.

Performance assessment of an organic Rankine–Vapor compression cycle (ORC-VCR) for Low-Grade compression heat recovery

Power consumption of the compression process in air separation units can be significantly reduced by precooling the inlet air of the air compressors with an organic Rankine cycle and vapor compression cycle (ORC-VCR). To date, most of existing researches on compression heat recovery focus on thermodynamic modelling and performance analysis. This paper presents an experimental assessment of a compression heat recovery system based on a mechanically coupled ORC-VCR for air separation units. Experimental investigations on the stabilities of gas bearing fluid supply system and motor cooling system were conducted. Results indicate that both are capable of maintaining stable operations while achieving the designed functions. System performance tests were performed with various mass flow rates, pressure ratios of high-temperature and low-temperature evaporating pressure. The increase in the ratio of two evaporating pressures leads to a dramatic decrease in the system coefficient of performance (COP). A COP of 0.63, a cooling capacity of 14.2 kW at a refrigeration temperature of 14.6 °C were achieved at a rotation speed of 25822 rpm with full-load operation. This work experimentally demonstrates an effective compression heat recovery system based on ORC-VCR, which suggests the potential application of the compression heat recovery system in air separation units.

Influence of refrigerant charge and condenser area on direct-expansion solar-assisted heat pump system for radiant floor heating

As known, the refrigerant charge and condenser area have important influence on the thermal performance of a heat pump system. A test rig of a direct-expansion solar-assisted heat pump (DX-SAHP) system for radiant floor heating has been built, and the quasi-dynamic mathematical model of the system has also been established, which uses propane (R290) as the refrigerant. The deviations between the simulated results and experimental data are within 7.1 %, showing a good agreement. The analysis reveals that, when the refrigerant charge of the DX-SAHP system increases, the condensing pressure and the subcooling degree in the condenser increase, while the evaporating pressure decreases, resulting in the increase of the effect heat gain and the compressor power. The system coefficient of performance (COP) first increases to a maximum and then decreases with the refrigerant charge, and remains at a relative high level within a certain range near the optimal refrigerant charge. The optimal refrigerant charge is independent of solar insolation and ambient temperature, and decreases with initial water temperature in the hot water storage tank, while the corresponding subcooling degree is always in the 6–9 °C range. Furthermore, the system COP is also influenced by the condenser area. Both the maximum COP and corresponding optimal refrigerant charge are found to increase with the condenser area. As the condenser area increases from 0.553 to 1.393 m2, these two parameters increase by 8.95 % and 27.91 %, respectively.

Experimental performance of a vapor-injection CO2 heat pump system for electric vehicles in −30 °C to 50 °C range

Efficient and wide-range heat pump system is essential to improve the driving range and comfort of electric vehicles. In this paper, a vapor-injection transcritical CO2 heat pump system with a flash tank for electric vehicles was built up, and the heating and cooling performance in a wide range from −30 °C to 50 °C were experimentally studied. The maximum coefficient of performance (COP) at −30 °C/ 20 °C was 1.45, and the maximum COP at 50 °C/ 27 °C was 1.08. By comparing with the basic system without injection, it was found that the heating performance of the vapor-injection system was significantly improved, and the lower the outdoor temperature, the greater the improvement. The COP and heating capacity of the vapor-injection system were increased by 45.5 % and 75.7 % respectively at −30 °C/ 20 °C. Under the cooling conditions, only when the outdoor temperature was lower than 40 °C, the vapor-injection system had an advantage, and the maximum increments of COP and cooling capacity at 35 °C/ 27 °C were 9.5 % and 16.8 %, respectively. Further, a relationship model between vapor injection and compressor structure and operating conditions was established according to the working principle of the twin rotary compressor. The experimental verification showed that the deviation was within 8 %, which could provide a basis for the construction of the CO2 vapor injection heat pump system model.

Numerical simulation of a hybrid system using Peltier thermal switches in magnetic refrigeration

• A 2D transient model of a hybrid magnetic refrigeration system using Peltier modules as the heat switches was established. • The actual transient thermal response of the Peltier modules was considered in the model. • The comparison of the hybrid system with the AMR mode and the Peltier mode was done. • At 4.00 Hz and 0.20 A, the COP and cooling power density of the hybrid system exceeded that of the pure AMR mode. • The influence of operating parameters on the hybrid system performance was evaluated. To overcome the shortcoming of the low cooling power density in the ordinary magnetic refrigerator, a hybrid system using Peltier thermal switches in magnetic refrigeration has been proposed by researchers. In the system, the magnetic material is sandwiched between Peltier modules which are used as the thermal switches to transport the heat to and from the material undergoing the magnetic refrigeration cycle. To analyze the system, a two-dimensional transient model is established by considering the thermal characteristics of the Peltier module, which has not been done before. With the model, the performance of the hybrid system was firstly compared with that using the pure parallel plate active magnetic regenerator (AMR) mode and that using the pure Peltier mode. Compared with pure parallel plate AMR mode, the hybrid system using Peltier thermal switches in magnetic refrigeration can significantly increase the cooling power density at low frequencies (1.60 Hz – 4.00 Hz). In this frequency range, the coefficient of performance (COP) of pure parallel plate AMR mode decreased rapidly with the increase of frequency, while the COP of the hybrid system decreased slowly, and at 4.00 Hz and 0.20 A, the COP of the hybrid exceeded that of the pure parallel plate AMR mode. Compared with pure Peltier mode, the hybrid system can achieve the same cooling power with less power consumption and obtain a higher COP. Furthermore, the influence of operating parameters on the performance of the hybrid system, which included utilization factor, input current, the outlet temperature of the cold-end heat exchanger, frequency, and the number of refrigeration units, was investigated. The results show that, when using Peltier thermal switches, the actual transient thermal response of the Peltier module plays an important role in the hybrid system, which is ignored in previous literature. To achieve efficient operation at high frequency, when using Peltier thermal switches, the thermal response time of the Peltier modules as well as the Joule heating effect, etc, needs to be carefully evaluated.

Performance of Air-Conditioning System with Different Nanoparticle Composition Ratio of Hybrid Nanolubricant.

To reduce fuel consumption, the automotive air-conditioning (AAC) system's coefficient of performance (COP) needs to be improved. The use of a diverse selection of hybrid nanolubricant composition ratios is expected to improve the properties of single nanolubricants, resulting in improved AAC system performance. The goal of this study was to find the best combination of hybrid nanolubricants for the best performance of the AAC system. Al2O3-SiO2/PAG hybrid nanolubricants at 0.06% volume concentrations with various composition ratios (20:80, 40:60, 50:50, 60:40, and 80:20) were investigated. An initial refrigerant charge of up to 155 g and a compressor speed of up to 2100 rpm were used in the experiment. The cooling capacity, compressor work, and COP of the AAC system were measured to determine its efficiency. The COP enhancement and compressor work reduction were recorded up to 16.31% and 18.65% for the 60:40 composition ratio, respectively. The maximum cooling capacity up to 75.84% was recorded for the 80:20 ratio, followed by 60:40. The maximum COP value of 8.81 for 155 g of hybrid nanolubricants was obtained at 900 rpm with a 60:40 composition ratio. Therefore, for optimal performance in the AAC system, a 60:40 composition ratio of the Al2O3-SiO2/PAG nanolubricant combination is strongly recommended.

Effects of a Combined Geothermal and Solar Heating System as a Renewable Energy Source in a Pig House and Estimation of Energy Consumption Using Artificial Intelligence-Based Prediction Model.

Simple SummaryA combined geothermal heat pump and solar system (GHPS) was installed at a pig house to check the effects on electricity consumption, greenhouse gas emission (GHE), internal farm temperature, the concentration of noxious gases and growth performance. The GHPS heating system reduced energy consumption and CO2 concentrations. Furthermore, the GHPS system effectively maintained the optimum temperature for pig growth inside the pigsty. Additionally, the artificial intelligence (AI)-based model ‘gene expression programming (GEP)’ was used to predict electricity consumption.This experiment evaluated the performance of a combined geothermal heat pump and solar system (GHPS). A GHPS heating system was installed at a pig house and a comparative study was carried out between the environmentally friendly renewable energy source (GHPS) and the traditional heating method using fossil fuels. The impact of both heating systems on production performance, housing environment, noxious gas emission, and energy efficiency were evaluated along with the GHPS system performance parameters such as the coefficient of performance (COP), inlet and outlet water temperature and efficiency of solar collector. The average temperature inside the pig house was significantly higher (p < 0.05) in the GHPS heating system. Similarly, the outflow temperature was increased significantly (p < 0.05) than the inflow temperature. The results of COP and efficiency of the solar system also indicated that the GHPS is an efficient heating system. The electricity consumption and carbon dioxide gas concentration were also reduced (p < 0.05) in the GHPS system. This study also predicts electricity consumption using an artificial intelligence (AI)-based model. The results showed that the proposed model justifies all the acceptance criteria in terms of the correlation coefficient, root mean square value and mean absolute error. The results of our experiment show that the GHPS system can be installed at a pig house for sustainable swine production as a renewable energy source.

Design of a batch Ohmic heater and evaluating the influence of different treatment conditions on quality attributes of kinnow (Citrus nobilis × Citrus deliciosa) juice

A batch Ohmic heater (5 L) with a modified electrode arrangement was designed for quick and uniform heating of kinnow juice. A T-shaped arrangement and micro silver coating over stainless steel electrodes provided temperature variation of 0–2 °C across the system and a system performance coefficient of 0.96. The come-up time for 60–80 °C was 1.3–3 min at 180 V. Pectin methylesterase, the most resistant enzyme, was inactivated completely at (120 V/80 °C/1 min), (150 V/80 °C/30 s), (180 V/70 °C/10 s). No aerobic mesophiles, yeasts, and moulds were detected in these samples. Ohmic heating at 180 V did not influence the colour of the juice significantly; however, some samples showed a little elevation (by 0.2) in the pH. The reduction in vitamin C, antioxidants, and total phenols was 6–12% at 150 V/80 °C/30 s. The fuzzy analysis shows that the Ohmic pasteurized juice had the highest similarity score. Industrial relevancesA batch assembly (5 L capacity) of the Ohmic heater has been fabricated to make a shelf-stable kinnow juice. The produced juice is microbially safe, enzymatically stable, and retains maximum bioactive compared to conventional thermal treatment. Thus, Ohmic heated juice can fulfill the stakeholders' demand for microbial safety, enzymatic stability, and nutritional superiority. Industry can scale up the design of batch Ohmic heater for efficient and faster pasteurization of citrus juice like kinnow juice.

Performance Analysis of Solar Assisted Heat Pump Drying System with Dual Condensers

The main components of the dual condenser solar-assisted heat pump (SAHP)drying include the solar collector, evaporator, compressor, fan coil, twin condensers, expansion valve, and drying chamber. The solar drying process was assisted by a heat pump, and the optimal efficiency was determined by heating and dehumidifying the air, and recirculating the air that has been heated. The efficiency of the heat pump system was assessed by its coefficient of performance (COP), which is the percentage of the actual heat delivered by the heat pump to the total electrical power necessary to operate the heat pump. The average temperature of the drying chamber reached a temperature of 60 °C with a relative humidity of around 70%, and the system's COP was 5.546 with no contribution from solar energy or at no solar fraction (SF = 0). The same conditions in the drying chamber can be achieved at solar faction or SF = 0.83, with COP increased to 12.7.

Experimental study on the heating performance of transcritical CO2 heat pump for electric buses

In this paper, a transcritical heat pump using CO2 as the refrigerant was developed, and the heating performance test experiment was carried out in the standard bus air conditioning performance enthalpy difference laboratory to explore the influence of outdoor temperature, compressor speed and electronic expansion valve (EEV) opening on the performance of the heat pump system. Operating at −25 °C/20 °C (outdoor temperature is −25 °C, indoor temperature is 20 °C), the heating capacity (Q) of the CO2 heat pump is 10.5 kW, the coefficient of performance (COP) is 1.24, indicating that the system can also effectively save energy under ultra-low temperature conditions. As the compressor speed rises, the COP of system drops sharply, so the compressor operating frequency should be reduced as much as possible under the premise of satisfying the Q and outlet air temperature (Ta.out). Increasing the opening of the EEV can effectively reduce the compressor exhaust temperature (Tcom.out) and pressure(Pcom.out) to ensure the safe and stable operation of the system.

A Review on Experimental Analysis on Hybrid Vapour Compression Refrigeration System

Abstract: A vapor-compression refrigeration system is a system that uses liquid refrigerant in a closed system which circulates the refrigerant through four stages in which it is alternately compressed and expanded, changing it from liquid to vapor. As this change happens, heat is either absorbed or expelled by the system, resulting in a change in temperature of the surrounding air that is passing over the unit's components. Nearly all of the refrigeration systems we use today use this cycle to accomplish cooling. VCRS system is made up of four main components: the evaporator, condenser, compressor and expansion valve. The evaporator and condenser are both a series of coils that are designed to create more surface area for the refrigerant to react with. Meanwhile, the compressor and expansion valve are mechanical units that control the amount of pressure and temperature change that occurs between the two stages. It was named after Jean Charles Athanase Peltier, the physicist who discovered the effect in 1834. Peltier discovered that when current is made to flow through a circuit consisting of two different types of conductors, a heating or cooling effect is observed at the junctions between the two materials. This change in temperature at the junction is called the Peltier effect. When electric current is passed through a circuit consisting of two different conductors, a cooling effect is observed in one junction whereas another junction experiences a rise in temperature. This change in temperatures at the junctions is called the Peltier effect. The effect is found to be even stronger when two different semiconductors are used in place of conductors in the circuit. In this journal Two methods of refrigeration work together to get a good coefficient of performance (COP). The both vapour compression refrigeration method which good in control the inside temperature and peltier effect by combined together in a single setup. The heat generated from the two dissimilar semiconductors are used to change the complete phase transformation of the refrigerant system before entering into the compressor. The combined system we call it as hybrid experimental system. The COP of thermoelectric system in combined with VCRS is increased by proper heat dissipation, from hot side of the peltier units and these heat fluxes utilized by VCRS for its own benefit.

Numerical simulation of heat pump drying system for paper exhaust hood

Abstract In view of the present situation that the exhaust waste heat of the hot air hood in the paper drying section is too much and the environment is not friendly, a closed heat pump drying system model applied to the exhaust air hood is proposed and established. Effects of evaporation temperature and condensation temperature on supply air temperature, supply air moisture content, system performance coefficient (COP) and dehumidification energy consumption ratio (SMER) were studied. Results show that with the increase of condensation temperature, the supply air temperature is unchanged, and the moisture content of the supply air increase, while the COP and SMER of the system show a downward trend. The moisture content of supply air decrease with the increase of evaporation temperature, while the supply air temperature, COP and SMER all show an upward trend. Therefore, in order to improve the drying characteristics and improve the performance of the heat pump system, the condensation temperature can be reduced and the evaporation temperature can be increased.

Cooperative Optimization of A Refrigeration System with A Water-Cooled Chiller and Air-Cooled Heat Pump by Coupling BPNN and PSO

Aiming at the issues of unreasonable cooperation schemes and inappropriate setting of parameters of the refrigeration system with multi-chiller plants, this paper presents a cooperative optimization method to improve the energy performance of the system composed of water-cooled chillers and air-cooled heat pumps. The cooperative optimization process includes scheme optimization and parameter optimization. To content the dynamic cooling load, the working sequence of air-cooled heat pumps and water-cooled chillers with variable frequency chilled water pumps is first optimized. Based on the optimal scheme, a back-propagation neural network (BPNN) coupled with particle swarm optimization (PSO) is implemented to explore the preferred operating parameters of multiple chiller plants corresponding to the best coefficient of performance (COP). Compared with the performance of the initial operation module, the energy consumption of the water pump and fan decreases by over 50%, and the COP of the refrigeration system is improved by 16% (COP = 3.85) through the scheme operation. After parameter optimization, the total energy consumption is reduced by 21.7%, and COP is increased by 26.5% (COP = 4.20). Therefore, the proposed cooperative optimization method can provide useful operation guidance for the refrigeration system with multi-chiller plants.

Analysis of key influencing factors for multi-mode solar heat pump systems

To further improve the stability and renewable energy utilization of the compound heat source heat pump system under complex operating conditions, a multi-mode solar heat pump system was proposed and a mathematical model was established in this paper. The accuracy of the model is verified by the experimental data, with the relative error within ±15%. The effects of the number of solar photovoltaic/thermal (PV/T) collectors (area), environmental parameters, and refrigerant flow rate on system performance are discussed separately for different models by the validated model. The results show that (1) PV/T-water source heat pump mode: the number of PV/T collectors in parallel (area) increases to 3 (3.84 m2), and the system performance improves the most, subsequently weakening; (2) PV/T-water and air composite heat pump model: When the refrigerant distribution ratio in the double-pipe heat exchanger 1 is increased from 55% to 95%, the collector's heat collecting capacity, power generation efficiency, and system coefficient of performance (COP) increase by 8.99%, 1.22%, and 6.4%, respectively. Moreover, the increase in solar irradiance can promote more refrigerant flow into the double-pipe heat exchanger 1 and improve heat pump COP more than the effect of increased ambient temperature. The research results can provide an effective reference for further optimization of solar heat pump systems and full utilization of renewable energy.

Parameter optimization of multistage closed series heat pump drying system

In the heat pump drying system (HPDS), there are few studies on energy efficiency and system process optimization, so based on the basic principle of heat pump drying, this paper proposes a multistage closed series drying system for corn drying to strengthen the research gap. The drying system is simulated and researched by establishing mathematical model and programming with MATLAB software. The calculation results show that the coefficient of performance (COP) of the four stage closed heat pump drying system (HPDS) can reach about 5.5 in summer and 4.5 in winter; with the increase of the cooling temperature difference of the auxiliary evaporator, the COP values of system 1, 3 and 4 increase about 10% in summer, while the COP of system 2 is almost unchanged, and the COP changes of the four systems in winter are very small; the compressor powers increase except that of system 1. With the increase of the return air temperature, except that the COP of system 2 does not change much, the COP of the remaining systems decrease about 15% in summer and 5% in winter; the compressor power increases about 40 kW except for system 2 in summer and decreases largely in winter for each system. And the payback period of the system is about 1.22 years.

Techno-economic analysis of a PV/T waste heat–driven compound ejector-heat pump for simultaneous data centre cooling and district heating using low global warming potential refrigerants

A comprehensive techno-economic evaluation is evaluated based on an innovative compound ejector-heat pump system with PV/T (photovoltaic thermal) waste heat-driven. The aim of the system is simultaneous data centre cooling and waste heat recovery for district heating to reduce residential greenhouse gas emissions. The new system avoids the ejector pump by combining PV/T waste heat with an evaporative-condenser as an ejector driving force, considering several low global warming potential alternatives to R134a. The simulation indicates that the proposed system presents a remarkable difference in all investigated refrigerants’ overall system coefficient of performance (COP). Particularly, R515B presents the highest increase in COP, 54% and 49% in cooling and heating modes, respectively. It also provides the highest electricity consumption reduction, 84.1 MWh yearly. Moreover, the system improves the data centre power usage effectiveness (PUE) index from 10 to 19%. In financial terms, the shortest payback period (6.3 years) is obtained with R515B, followed by R515A and R1234ze(E).

Experimental study of R290 replacement R134a in cold storage air conditioning system

R290 refrigerant offers good environmental protection and thermodynamic characteristics. The feasibility of R290 replacing R134a was summarized through theoretical analysis and experimental tests in this paper. A coiled ice storage experimental test platform was built, and the performance of R290 and R134a cool storage air conditioning systems was analyzed. The experimental analysis confirmed that the R290 system has a higher volumetric refrigerating capacity, and the system COP (coefficient of performance) is comparable to the R134a system. At the same evaporation temperature, the pressure ratio and exhaust temperature of the R290 system are lower than those of the R134a system. In addition, the charge amount of the refrigerant can have an impact on cold storage performance. It was found that the optimal charge range of R134a is 1300–1400 g, and that of R290 ranges from 500 to 600 g. The optimal charge amount for R290 is only 43–46% of R134a. A lower charge amount is beneficial to reduce the explosion risk of the R290 cool storage air conditioner. Under the optimal charge, the R290 system has a fast cooling rate and shorter cooling storage time, and the average specific refrigerating effect is increased by approximately 52% compared with R134a.

Integration of desiccant wheels and high-temperature heat pumps with milk spray dryers

Heat pump technologies are promising to decarbonise industrial drying processes by improving energy efficiency and shifting the energy source from fossil fuels to renewable-sourced electricity. While desiccant materials have proved effective in improving drying efficiency for dryers at temperatures < 120 °C, this paper focuses on the performance of desiccant wheel assisted high temperature heat pump (HTHP) technology to heat the dryer inlet air up to 150 °C using heat recovered from the dryer exhaust. Thermodynamic models of heat pump cycles were established to evaluate the performance of all the HTHP components. A one-dimensional finite difference model was used to simulate the dehumidification of exhaust air through the evaporator of the HTHP. The performance of the desiccant wheel was numerically simulated considering only the gas-side heat and mass transfer resistance. When compared with configurations of a simple HTHP, the desiccant wheel assisted HTHP requires a much smaller evaporator size (50–60 % less than the simple HTHP), similar to the HTHP with a heat recuperator. Its improvement in overall system coefficient of performance (COP), exergy efficiency and the drying capacity when applied to a spray dryer is marginal when compared to the model accuracy. However, comparisons between two cases with different ambient conditions (15 °C and 60 % RH vs 25 °C and 80 % RH) show that such improvement by the desiccant wheel assisted HTHP develops with increasing humidity in the incoming drying air.

Structure-improved current collector for performance enhancement of electrolyte membrane dehumidifiers: 3D simulations and in-situ measurements

Electro-dehumidification based on proton exchange membrane (PEM) is promising owing to its compact assembly and convenient operation. By numerically improving the effects of current collectors’ structure on the operation performance (moisture removal rate, current/temperature/humidity distribution and energy utilization rate), this research achieved a significant dehumidification enhancement (more than 40%) for electrolyte membrane dehumidifiers. 3D Multiphysics simulation and in-situ verification measurements were conducted. Compared with the original collectors, the dehumidification rate can be enhanced by 35% with the “口” collectors, and by more than 40% with “X”, “#” and “▪” collectors. The best performance occurred with the anode collector of “▪” structure (opening area: 9 × 10-4 m2), which the rate increased by 46%. The improvement effects were mainly due to the improvement of potential distribution (especially on the anode side) and the concentration of the reactant (water vapor) reaching the catalyst interface. Compared with the “口” type, the current density uniformity of membrane dehumidifier with the “▪” collector increased from 0.0033 to 0.032. The temperature and moisture distribution were also more uniform. The opening structure of anode collector resulted in a more significant effect than the opening area. Therefore, the system energy utilization rate and COP (coefficient of performance) can be doubled, up to 3.48 × 10−2 g·J−1·m−2 and 0.26, respectively. This research provides a theoretical basis and practical direction for improving current collectors of PEM dehumidifiers.