Inlet Air Humidity Research Articles

Investigating dehumidification and heating performance in a dual evaporator heat pump system for electric vehicles

In cold, moisture-rich winter environments, window fogging represents a substantial safety hazard for drivers. Electric vehicles often incorporate heat pump systems to address challenges such as dehumidification and heating specific to cold weather. Therefore, it is essential to evaluate the dehumidification and heating efficiency of these systems through focused research. This study presents a dual-evaporator heat pump system designed specifically for electric vehicles, equipped with two distinct modes for dehumidification and heating. The research examines how factors such as inlet air volume and the degree of opening of the electronic expansion valve affect the system's dehumidification and heating performance. Experimental analyses were conducted to explore the system's response under various conditions of inlet air humidity and compressor speed in both modes. Results suggest that increasing inlet air volume improves dehumidification effectiveness but may reduce heating performance. Likewise, a wider opening of the electronic expansion valve enhances heating but could decrease dehumidification efficiency. Importantly, the study indicates that when the relative humidity of the inlet air exceeds 70 %, a single evaporator mode is more effective for dehumidification. However, when the relative humidity is below 70 %, the dual evaporator mode is more advantageous, showing better heating performance.

Insight into the mechanisms and in-plane reaction heterogeneity of the dynamic response of proton exchange membrane fuel cells

The voltage undershoot is one of the main dynamic problems of proton exchange membrane fuel cells (PEMFCs) under dynamic loadings. However, its mechanisms remain poorly understood due to its complex and coupled influencing factors. Besides, PEMFCs with a large active area are more prone to local dynamic failures for their pronounced in-plane (I-P) heterogeneity, while few studies have focused on the I-P heterogeneity of the dynamic response of large-area fuel cells. In this work, the mechanisms and the I-P heterogeneity of the voltage undershoot of a 320 cm2 PEMFC are thoroughly studied based on an in-situ monitoring method and a voltage loss decoupling method. Results show that the voltage overshoot is primarily driven by the ohmic loss (OL) overshoot and the concentration polarization (CP) overshoot. Results also prove that the OL overshoot is mainly caused by the instantaneous water shortage in the proton exchange membrane (PEM) which depends on the initial water content in the PEM. Besides, the CP overshoot is due to the instantaneous reactant shortage at the catalyst, and it is much sensitive to the change in the oxygen diffusion coefficient of the ionomer caused by the change in its water content. Meanwhile, both OL overshoot and CP overshoot demonstrate significant I-P heterogeneities under poor dynamic operating conditions, especially in cases of high load step and low inlet air humidity. Finally, the influences of operating conditions on the voltage undershoot and its I-P heterogeneity are discussed, and suggestions for improving the dynamic performance of PEMFCs are proposed.

A Study on the Conditions of Fog Generation and the Change Rule of Fog Zone Length in Air Intake Roadway

Fog in mine air intake roadways is a non-negligible disaster that seriously reduces the visibility of the roadway, affects vehicle transportation and the safe passage of personnel, and jeopardizes the safe production of the mine. This paper applies both field testing and numerical simulation to explore fog formation conditions and the effects of inlet air temperature and humidity on the fog zone length within the Wangjialing Mine’s air intake roadway in Shanxi, China. First, based on the consideration of the relationship between the moisture gain of surrounding rock and the temperature with humidity of the air flow, the fog generation and distribution law model of the air intake roadway was established. Based on this model, the critical inlet air temperature and the critical inlet air relative humidity for fogging in the Wangjialing Mine air intake roadway were determined. In addition, we found that the fogging point inside the roadway shifted forward continuously with the increase in inlet air temperature and inlet air relative humidity, and the length of the fog zone expands parabolically in response to these rising conditions.

A new strategy of dual-material reactors for stable thermal output of sorption thermal battery

Sorption thermal battery driven by air humidity is a promising alternative technology to traditional methods of burning fossil fuels for space heating. Its dominant design of one-material reactor faces technical bottlenecks of unstable discharging thermal output and low energy efficiency. Herein, a new strategy of cascaded dual-material reactors was proposed as a solution, by utilizing their different sorption characterizations at material level and “reaction wave” properties at system level. A proof-of-concept prototype was established, whose main and regulatory reactor were packed with AA-15% LiCl composite and SrBr2·H2O, respectively. Experimental results demonstrated that the regulatory reactor has a strong stabilization function of the unstable output temperature of the main reactor, with the average output temperature fluctuations under 1.5 °C. The discharging/charging energy efficiency was increased by 0.4–1.7 times compared with one-material reactor. The output temperature level and heating power can be simply adjusted by changing the inlet air humidity and air velocity. Moreover, the influences of the lengths of two reactors on the thermal output and system operations were evaluated. Possible strategies to further enhance the multistage utilization of the charging energy were proposed. This new design strategy can contribute to the popularization and application of sorption thermal battery.

A dynamic model of the packed dehumidifier

Liquid desiccant dehumidification, a clean energy technique for creating comfortable environments has received a lot of interest. Several dynamic models have been proposed to predict the outlet air humidity ratio and temperature, however, a study on presenting variations of heat and mass transfer coefficients and thermal mass of desiccant during the dynamic dehumidification process was not encountered according to authors’ best knowledge. This gap is primarily due to the complex nature of the coupled heat and mass transfer processes, which make it challenging to capture the evolution of heat and mass transfer coefficients over time. In this study, variations of these parameters are analyzed at first. A theoretical study is conducted to show the thermal mass of the desiccant can be considered constant when changing the inlet air humidity ratio or desiccant temperature, simplifying the dynamic modeling process. While the variation of heat and mass transfer coefficients show significant impact in such conditions. Subsequently, a new method based on mass conservation is provided to determine the thermal mass of desiccant. By examining the cause-and-effect relationships between heat and mass transfer coefficients and outlet air humidity ratio, the evolution of heat and mass transfer coefficients following exponential laws is deduced by inversion. Then a dynamic model of packed dehumidifiers can be completed easily based on above derivations, and its viability is confirmed by experimental results. Compared to the existing method, the prediction accuracy can improve by 50% based on the proposed methods. This study characterizes evolution rules of heat and mass transfer coefficients over time, and with this, evolutions of outlet air parameters during the dynamic dehumidification process can be acquired conveniently based on the existing steady dehumidification model.

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.

Numerical study of falling film dehumidification performance on corrugated plates

Due to a number of benefits, liquid desiccant dehumidification has received a lot of attention lately. In comparison to previous improvement strategies, corrugated plates have demonstrated higher efficacy in liquid desiccant dehumidification. This study employs computational fluid dynamics to examine the dehumidification performance of falling film liquid desiccant dehumidification on over sinusoidally shaped corrugated plates. The effects of plate geometries, solution parameters, and moist air (concentration of humidity, temperature, and flow rate) were discussed. Additionally, a mass transfer correlation was proposed based on the current numerical data. It is indicated that the corrugated plate significantly enhances dehumidification performance due to the liquid film waves intensification, mass transfer area expansion, and induction of vortexes close to the gas-liquid interface. The most effective falling film dehumidification is achieved using a corrugated plate with a wavelength of 5.0 mm and an amplitude of 0.5 mm. By raising the solution or air inlet temperature, the dehumidification rate is reduced while being strengthened by raising the solution or air inlet concentration, velocity, or air humidity. While decreasing when solution intake concentration or air velocity rises, the efficacy of dehumidification rises as solution velocity does. The proposed mass transfer correlation accurately predicts 93.3 % of the 45 data, with an error of 11 % or less. In the current parameter scopes, the magnitude has a more significant effect on Shair than the wavelength. Adjustments to air velocity and solution concentration can cause significant fluctuations in Shair, while air and solution temperature have little effect on Shair.

Performance Assessment of Solar Desiccant Air Conditioning System under Multiple Controlled Climatic Zones of Pakistan

Over the past decade, the integration of desiccant technology with evaporative cooling methods has proven to be highly effective and efficient in providing comfortable indoor environments. The performance of desiccant-based direct evaporative cooling (DEC) systems is strongly influenced by environmental conditions, and their output behavior varies across multiple climatic zones. It is not easy to assess the system performance in numerous climatic zones as it is a time-consuming process. The current study focuses on determining the feasibility of a solid desiccant integrated with a direct evaporative cooler (SDI-DEC) for three different climatic zones of Pakistan: Lahore (hot and humid), Islamabad (hot and semi-humid) and Karachi (moderate and humid). To serve this purpose, a specially designed controlled climate chamber with an integrated air handling unit (AHU) was installed to create multiple environmental conditions artificially. It could also provide global climatic conditions under temperature and absolute humidity ranges of 10 °C to 50 °C and 10 g/kg to 20 g/kg, respectively. The weather conditions of the selected cities were artificially generated in the climate chamber. Based on different operating conditions, such as inlet air temperature, humidity and regeneration temperature, the performance of the system was estimated using performance indicators like COP, dehumidification effectiveness, solar fraction and supply air conditions. Results showed that the maximum temperature achieved from solar collectors was about 70 °C from collectors with an area of 9.5 m2. Moreover, the observations showed that when the regeneration temperature was increased from 60 °C to 80 °C, the COP of the system decreased about 41% in a moderate and humid climate, 28% in a hot and semi-humid environment and 23% in a hot and humid climate. The results revealed that an SDI-DEC system has the potential to overcome the humidity and cooling loads of the multiple climatic scenarios of Pakistan.

Effect of Inlet Air Humidity Control on a Novel Indirect Condensative Cooling Performances in Achieving Air Thermal Comfort

The objective of this research is to investigate the effect of controlling inlet air relative humidity on the performance of solid dry pad based indirect condensative cooling (SDP-ICC) system, in an effort to have a better air thermal comfort. The main evaporative cooling parameter such as cooling efficiency, cooling capacity, and temperature drop, condensation rate and energy efficiency ratio would be observed, together with the final dry and wet bulb air temperature and relative humidity in respect to reach the standard air thermal comfort. During the experiment test, the inlet air would be heated respectively using 1.0 kW, 1.5 kW and 2.0 kW heater in a climate chamber before it passed through to the solid dry pad, to be cooled indirect condensatively. The air velocity would be set on 11.3 m3/. The test results indicate that to achieve an air thermal comfort significantly in the evaporative and or condensative cooling system, the air should need to be treated with more than one thermal process, rather than cooling only. In this research, the SDP-ICC has only achieved the air thermal comfort in respect to its relative humidity of 67.3%, 55.65% and 44.3% respectively for heating capacity of 1.0 kW, 1.5 kW and 2.0 kW. The highest SDP-ICC cooling performance has been achieved on 1.5 kW heating capacity, in which it has reached 1.9 kW, 1.83, 3.4oC and 0.237 m3/hr respectively for cooling capacity, energy efficiency ratio, temperature drop and condensation rate. It can be concluded that by heating the inlet air relative humidity in evaporative and or condensative cooling system, it can be resulted the product air which has met the standard air thermal comfort.

Development of artificial neural network models for indirect evaporative coolers in multi-climate regions based on field measurement

Data-driven artificial neural networks (ANN) based on data drivers with their powerful self-learning capability and high adaptability are gaining increasing attention for the application in modeling indirect evaporative coolers (IEC). However, most ANN models of IEC in existing studies are either limited to a specific climate region or conventional IEC configurations. In this paper, a multi-region back-propagation (BP) neural network model for predicting the performance of advanced dew-point IECs is developed. Operational data for ANN model development were collected through field measurements in IEC projects in three typical climate zone cities in China (Dunhuang, Yulin, and Fuzhou), covering arid, moderately wet, and humid regions. A comparative study of three single-region neural network models was conducted in terms of both convergence characteristics and statistical performance metrics. Each model contains two input variables (inlet air temperature, inlet air humidity) and one output variable (wet-bulb efficiency). The results show that the model fits best in Yulin, followed by Dunhuang and Fuzhou, with total correlation coefficients of 0.9918, 0.9477, and 0.8946, respectively. The predicted values of wet-bulb efficiency are in good agreement with the actual operating data, and the deviation of almost all predicted values is within ±10%. Practical application The application values of IEC ANN models are as follows. First, the IEC-ANN model can predict IEC performance adaptively based on dynamic operational data. Therefore, it can provide the best operating strategy and design parameters for different situations. In addition, it can provide a fast response to guide the system operation when auxiliary control is required. Most importantly, this new approach requires only a limited number of tests rather than exhaustive experimental studies or dealing with complex mathematical models, and future manufacturers can use neural network technology to evaluate the performance of dew-point indirect evaporative coolers, thus saving engineering budget and time.

Experimental and modeling study of bubble absorption-based deep dehumidification using the ionic liquid: Parametric analysis on heat and mass transfer

Conventional liquid desiccant dehumidification is good at humidity control with energy conservation and stable operation, but is limited by corrosion and crystallization in deep dehumidification. Thus, it is necessary to broaden the humidity adjustment range of liquid desiccant deep dehumidification as well as avoid corrosion. Ionic liquids (ILs) with deep dehumidification potential (e.g., extremely low vapor pressure and non-corrosion) are a promising alternative to traditional salt solutions. Meanwhile, the bubble absorption-based mode can obtain a huge gas–liquid specific interfacial area, which is expected to solve the low wettability and insufficient gas–liquid transfer efficiency in traditional falling-film/packed dehumidifiers using IL. In this work, the bubble absorption-based deep dehumidification using IL (BADD-IL) is investigated. Meanwhile, the heat and mass transfer mathematical model of BADD-IL is established, and a bubble column dehumidifier using the novel IL is experimentally examined under different conditions. The results indicated that the deep dehumidification performance is strongly dependent on operating parameters, and the minimum outlet air humidity ratio is around 1.2 g/kgda. In particular, it is most sensitive to inlet air humidity ratio, followed by liquid height and superficial velocity, and the effect of solution temperature is the least. Notably, the influential mechanism of superficial velocity and solution temperature on volumetric transfer coefficient is different. The increase of superficial velocity promotes both gas–liquid specific interfacial area and heat and mass transfer coefficient. For the IL with lower temperature, its higher heat and mass transfer coefficient makes up for the poor specific interfacial area caused by high viscosity. Additionally, the Lewis factor of bubble column dehumidifier using the novel IL is basically less than 0.6, which is important for the device design and scale-up. This study clarifies the heat and mass transfer mechanism of BADD-IL, and provides guidance for the development of ILs deep dehumidification technology.

Experimental study of compressor electric current detection for a split-type air conditioner affects energy savings

The paper presents an experimental study that aims to measure the compressor electric current of a split-type air conditioner for analyzing the various abnormal condition of the R-32 refrigerant pressure, especially for detecting compressor electric current while occurring dirt in the evaporator coil and condenser coil. The method was to install sensor devices to measure the temperature and humidity of inlet air and outlet air, and the velocity of the air outlet of the evaporator unit. In condenser unit was to measure the electric current compressor and electric power input. All data from sensors send to the Arduino board and using Parallax Data Acquisition (PLX-DAQ) Excel Macro for the record. The results show physical behavior and the changing of compressor electric current according to the abnormal condition of the refrigerant system, blocking of condenser and evaporator coil.

Evaluation of new dew point evaporative cooler heat and mass exchanger designs with different geometries

In this study four new geometries of heat and mass exchanger for dew point evaporative cooling are investigated and their performance is compared to that of the commonly used flat plate and corrugated plate exchangers. In the proposed exchangers, each dry channel is completely enclosed by its adjacent wet channels, and each wet channel is completely enclosed by its adjacent dry channels (related detailed information is presented graphically in this paper). In addition, a robust numerical model was developed and is examined under various operational and geometrical conditions. The analysis showed that the proposed dew point evaporative coolers improve the chilled air temperature, water consumption, cooling capacity, and energy efficiency. In particular, the circular concentric tube exchanger, under certain operating conditions (inlet air temperature, humidity ratio, and velocity of 40°C, 6 g/kg, and 3 m/s, respectively), could produce the lowest chilled air temperature of 9.6°C and the highest wet bulb and dew point effectiveness of 148% and 99%, respectively. Additionally, water consumption is reduced to 1.34 L/hr for an inlet air velocity of 1 m/s. A triangular tube exchanger achieved the highest cooling capacity and coefficient of performance, but consumed the largest amount of water. Our geometrical analysis demonstrates that the overall performance of dew point evaporative cooling systems can be improved by employing new geometries for heat and mass exchanger channels. Practical application: The dew point evaporative cooler is an environmentally friendly air conditioning system used in buildings. It is considered the strongest candidate to replace vapour-compression refrigeration systems because it consumes considerably less electricity while achieving high performance. Our research demonstrates that through revised geometry it is possible to further improve the performance of the system leading to improved energy and water efficiency.

Theoretical study on the wetting rate in wet channel of dew-point evaporative cooler based on Marangoni effect

Dew-point evaporative cooler is widely concerned as a fresh air precooling system, for its high efficiency, energy saving and environmental protection. A mathematical model for a plate-type counter flow dew-point evaporative cooler is developed in the paper, in which the film shrinkage induced by the Marangoni effect is taken in account. The results show that the model based on Marangoni effect has a higher accuracy compared to the model with wetting rate σ = 100%, in which the Average Relative Deviation from the experiment decreases by 15.8%. The wettability distribution characteristics are investigated. Along the air flow, the transverse contraction distance of film is varied, which mostly depends on the evaporation process. The higher inlet air temperature, the lower inlet air humidity, the higher velocity of inlet air, the larger channel gap, and the higher ratio of working air to inlet air would cause the higher Marangoni number and lower wetting rate. Further, a constant value of wetting rate 96.2% is recommended to simplify the calculation, while the Average Relative Deviation of the simulated results compared to the actual process is only 0.47%.

Assessing Indoor Climate Control in a Water-Pad System for Small-Scale Agriculture in Taiwan: A CFD Study on Fan Modes.

Heat stress poses a significant challenge to egg production in layer hens. High temperatures can disrupt the physiological functions of these birds, leading to reduced egg production and lower egg quality. This study evaluated the microclimate of laying hen houses using different management systems to determine the impact of heat stress on productivity and hen health. The results showed that the ALPS system, which manages the hen feeding environment, effectively improved productivity and decreased the daily death rate. In the traditional layer house, the daily death rate decreased by 0.045%, ranging from 0.086% to 0.041%, while the daily production rate increased by 3.51%, ranging from 69.73% to 73.24%. On the other hand, in a water-pad layer house, the daily death rate decreased by 0.033%, ranging from 0.082% to 0.049%, while the daily production rate increased by 21.3%, ranging from 70.8% to 92.1%. The simplified hen model helped design the indoor microclimate of commercial layer houses. The average difference in the model was about 4.4%. The study also demonstrated that fan models lowered the house's average temperature and reduced the impact of heat stress on hen health and egg production. Findings indicate the need to control the humidity of inlet air to regulate temperature and humidity, and suggest that Model 3 is an energy-saving and intelligent solution for small-scale agriculture. The humidity of the inlet air affects the temperature experienced by the hens. The THI drops to the alert zone (70-75) when humidity is below 70%. In subtropical regions, we consider it necessary to control the humidity of the inlet air.

Parametric investigations on a novel bubble column liquid desiccant dehumidifier with internal cooling

Increasing demand for space cooling and proportionate demand for electrical power call for less power intensive technology with lower carbon footprint. The liquid desiccant (LD) based air conditioning systems can remove latent heat more efficiently, mainly using heat energy coming from waste or renewable energy source. A novel, simple and corrosion-free bubble column liquid desiccant air dehumidifier (BCLD_ADH) with provision for internal cooling of LD has been developed in this work. The advantages of providing internal cooling and effect of LD concentration as well as ambient conditions are evaluated in this experimental work. Two new type of effectiveness, one based on ambient wet bulb temperature and the other on crystallization temperature of LD are proposed here to give due credit to higher potential of moisture removal available in internally cooled dehumidifier. At 40% concentration of LD, the dehumidifier effectiveness at wet bulb temperature was 67% for adiabatic dehumidifier, but could be increased to 95% using internally cooled dehumidifier. Using higher concentration is necessary for adiabatic dehumidifier but less important for internally cooled dehumidifier as lower LD temperature helps retain higher potential for mass transfer. The inlet air humidity ratio helps to increase change in humidity ratio while higher mass flow rate also helps increase moisture removal rate proportionately.

Design of New Test System for Proton Exchange Membrane Fuel Cell

A comprehensive test system for proton exchange membrane fuel cells (PEMFCs) is designed and developed for monitoring and controlling the inlet and outlet parameters and safety issues of fuel cells. The data acquisition and output instruction rely on the connection between PLC (programmable logic controller) and OPC (object linking and embedding for process control). Based on Siemens S7-200 series PLC and PID (proportion integration differentiation) technology, the margin of error in relative humidity of inlet air is controlled at less than 0.7%. Furthermore, a hydrogen recycling system and an alarm module are introduced, considering the hydrogen or nitrogen solenoid valve power failure, cooling fan power failure, temperature anomaly, and hydrogen leakage. This developed test system is evaluated by the experimental investigation of PEMFC performance. The results show that the test system has very good test and control performances. At a cell temperature of 40 °C, enhanced performance in the polarization tests is depicted at a high humidification temperature of 60 °C.

Three-dimensional numerical analysis of fin-tube desiccant-coated heat exchanger for air dehumidification in tropics

High-performance desiccant-coated heat exchangers (DCHEs) can be employed in air-conditioning systems to improve energy efficiency. While there are significant developments in experimental studies, theoretical approaches for analyzing the DCHE are impeded by the complex and coupled heat and mass transport mechanisms. Therefore, a 3D mathematical model has been developed in this work to study the dehumidification performance of a DCHE. Unlike other works reported in the literature, the developed model is able to simulate the complex coupling between heat and mass transfers in the entire volume of the heat exchanger. The model is calibrated and validated with experimental data, and a maximum discrepancy of ±8 % is recorded. A time-dependent study on the performance of the DCHE is carried out to understand the distribution of temperature, reaction rates, and water uptake in the heat exchanger. Effects of key influencing operational factors are investigated and discussed. It is indicated that the DCHE enters a stable performance state regardless of its initial adsorption state. The regeneration time should be equal to the dehumidification time to optimize the performance. A higher thermal COP is achieved under lower cooling/regeneration temperature, lower air flowrate, and shorter half-cycle time, while higher inlet air humidity ratio. Higher coated desiccant mass also provides a higher thermal COP, but this enhancement levels off once the coating grows. For DCHEs with less coating, reducing cycle time is recommended over increasing the coating amount.

Research on anti-frosting potential of air source heat pump evaporator in hot-summer and cold-winter zone

In this paper, the performance curve of a heat pump evaporator under critical frosting conditions was fitted. The functional relationship between the refrigerant evaporation temperature and the absolute air humidity ratio was obtained. In addition, the transfer unit model of the air source heat pump (ASHP) evaporator was established. The inlet air temperature, humidity ratio, velocity, fin pitch, and row number of evaporators were considered as input parameters. The anti-frosting potential of the heat transfer unit was simulated under critical frosting conditions. The results showed that, based on the heating potential of moist air unit mass under critical frosting conditions, the heating potential is at its minimum at an air humidity ratio of 3.39 g/kga. The maximum difference between the minimum temperature on the fin surface and the refrigerant evaporation temperature was found to be only 0.06 °C. The study findings highlighted that controlling the refrigerant evaporation temperature above the critical frosting temperature is an important method to prevent the evaporator from frosting. Under a low temperature environment, with the increase in the fin pitch and the inlet air velocity, the anti-frosting regulation performance of the two tube rows evaporator was found to improve compared to the single tube case. The aim behind increasing the inlet air velocity is to increase the heat transfer temperature difference between the inlet air and the critical frosting conditions. After optimizing the evaporator’s structural and operational parameters, the evaporator’s fin pitch is set according to the ambient air temperature. This was successful in meeting the requirement that the evaporator does not frost most of the time. Moreover, by adjusting the inlet air velocity, the evaporator will not frost at other times. In hot-summer and cold-winter zone, the operation of the ASHP evaporator with no frost can be achieved.

Evaporative cooling performance characteristics in ice thermal energy storage with direct contact discharging for food cold storage

In a vapor-compression refrigeration system for the cold storage of food, latent heat transfer not only adversely affects the freshness of food but also reduces energy efficiency. This study aims to investigate the evaporative cooling performance characteristics of ice thermal energy storage (ITES) with direct contact discharging for food cold storage to minimize latent heat transfer. Laboratory-scale test facilities were constructed for the ITES with direct contact discharge for evaporative cooling. The performance characteristics of the ITES with direct contact were measured and analyzed according to the conditions of the inlet air (temperature and humidity) and control parameters (face air velocity and ice amount). It is necessary to select an appropriate amount of ice at the maximum face air velocity for food cold storage. Therefore, for fresh foods with a low weight loss rate, such as potatoes, the amount of ice with the maximum COP should be set, whereas for fresh foods with a large weight loss rate, such as mushrooms, it is appropriate to select the minimum amount of ice to maintain a low weight loss rate.