EC Directive Research Articles

Hybrid liquid desiccant air-conditioning system with a direct expansion evaporative cooler

There is a need to control air temperature and humidity in humid regions, especially when fresh air is demanded. This study investigates the performance of a hybrid liquid desiccant (LD) air-conditioning system with a direct expansion (DX) evaporative cooler. Temperature, relative humidity, and power consumption were measured and reported using a wireless data-logging system at the air conditioning unit's key locations. The results showed that the hybrid unit reached a 34 % saving in the cooling load. In addition, the air hybrid liquid desiccant air-conditioning system with the direct expansion evaporative cooler saved about 32% in power consumption, compared to an uncooled desiccant air conditioning system that saved 23%.

NUMERICAL STUDY OF THE EFFECTS OF EVAPORATIVE COOLER SUPPLY AIR OUTLET HEIGHT ON THERMAL COMFORT

Thermal comfort in a space equipped with a direct evaporative cooler is a function of the height of the cooler's supply air outlet. This article attempts to numerically investigate the impact of hybrid downdraft evaporative cooler (HDEC) supply outlet height on occupant thermal comfort in an office building. DesignBuilder CFD parametric simulations was carried out by varying the height of the HDEC supply outlet from 0.1m to 2.4 m, step 0.1 m above ground level, using Predictive Mean Vote (PMV) as an objective function. The results show that the best PMV of -0.27 was obtained at 0.4m above the floor level.

Гігієнічні аспекти використання харчових добавок (лекція)

The significant expansion of international trade in food additives (FA) made it necessary to solve the problem of the expediency of using FA in the production, packaging, storage, transportation and sale of food products (FP). In Ukraine, the use of FA is regulated by the "Sanitary Rules for the Use of Food Additives", which fully meet international requirements. To improve the international trade of FP containing FA, the Council of the EU developed and tested a rational system of digital codification of FA with the letter "E" and a three- or four-digit number (code) assigned to a specific FA. It is included in Codex Alimentarius, EC Directives, FAO/WHO as an international digital codification system. The FA code confirms that this compound has been tested for safety, established purity criteria and hygienic standards for FP. In accordance with the Law of Ukraine "On the Safety and Quality of Food Products", the sale and use of domestic and imported food products without labeling in the national language about the composition of the food product with a list of the names of FA that were used in the process of its manufacture is prohibited. The majority of FA do not affect the body of consumers, are inert in used quantities, but some of them are capable of causing an adverse effect on the human body when ingested in significant quantities, therefore their hygienic regulation is extremely necessary.

Validated open-source Modelica model of direct evaporative cooler with minimal inputs

Direct evaporative coolers (DECs) are a low-energy cooling alternative to conventional air conditioning in hot-dry climates. The key component of DEC is the cooling pad, which evaporatively cools the air passing through it. While detailed numerical models of heat and mass transfer have been proposed for the cooling pad, these require many input parameters that are not readily accessible. Alternatively, simplified models lack accuracy and are confined to common types of cooling pad. To address these limitations, we developed and validated a physics-based model, that only needs the nominal data to compute the heat and mass transfer with considerable accuracy. The proposed model is implemented in Modelica, an equation-based object-oriented modeling language. For comparison, a basic lumped model from EnergyPlus based on the efficiency curve of the cooling pad is also implemented. The physics-based model exhibits <2% error from the experimental data and the lumped model exhibits a 12.3% error.

Evaluation of evaporative cooler models using cotton-based fabric pads for tropical housing units

Direct evaporative cooling (DEC) is a passive cooling strategy adopted in predominantly hot regions to restore building thermal comfort with less energy consumption and minimum impact on the environment. The implementation and studies of DEC in tropical housing are limited. Although DEC can reduce air temperature, an increase in relative humidity can still be seen as a disadvantage. Many materials were introduced for the cooling pads, but none was explicitly proposed for use in the housing unit. The present study explores different cotton-based fabrics to be used in the proposed evaporative cooler of the public housing unit in Surabaya. It analyses its ability to reduce air temperature and identify the increase in air humidity that may occur. A small-scale model of the housing unit that incorporates an evaporative cooling system is set, and internal air temperature and humidity are recorded. Results of the analysis show that different fabric specifications can lead to various thermal performances. A cotton-based blanket is found to be suitable for the proposed strategy.

Use of Secondary Metabolites of Wood-Decaying Fungi to Reduce Damping off Disease

Phytopathogenic fungi can cause plant diseases that are difficult to control, including mass mortality of some tree species. The Fusarium oxysporum complex (sensu lato) is one of the most dangerous groups of phytopathogenic fungi, causing the death of conifer species, including Pinus sylvestris seedlings in forest and ornamental nurseries. Recently, non-chemical methods of plant protection have become the basis of integrated pest management (IPM) in the European Union (EC Directive). The possibility of protection of pine seedlings against the pathogen F. oxysporum using active substances from wood-destroying fungi commonly found in forests was examined. Methanolic extracts of Fomitopsis pinicola, Ganoderma applanatum, and Trametes versicolor were found to contain substances effective in both prevention and treatment of infected seedlings. G. applanatum and T. versicolor showed particular biological activity in increasing plant resistance. Efficacy, especially of the extract of F. pinicola, increased with concentration. Further field trials are needed to confirm the results obtained in laboratory tests on plant protection.

Experimental performance evaluation of date palm fibers for a direct evaporative cooler operating in hot and arid climate

This paper presents an experimental investigation of a direct evaporative cooler, DEC, designed and installed in the hot and arid region of Biskra, Algeria. Date palm tree fibers are used as a novel evaporative cooling material. Different performance parameters are experimentally tested to assess the thermal performances of the DEC system. Results show that the cooling capacity, cooling efficiency and total cooling capacity of the pad improve by increasing the pad thickness and air mass flow rate in extreme ambient conditions. Besides, operation duration has no remarkable effect on the DEC performance. The operating parameters (pad thickness, air mass flow rate, ambient conditions, quantity and temperature of water) are the determinant factors to reach the optimum operating conditions of DEC. Finally, a comparison with the usual cooling systems shows that the date palm fibers pad is an effective material compared to the conventional pads in hot and arid zones.

Performance evaluation of a solar powered solid desiccant evaporative cooling system with different recirculation air ratios

The evaporative cooling technology (ECT) has been regarded as an effective alternative to conventional vapour compression systems due to its energy saving and eco-friendly features. Moreover, when integrating with a solid desiccant unit, ECT can further extend its application in hot and humid environments. This paper proposed and evaluated a solar-assisted solid desiccant Maisotsenko cycle (M−cycle) based indirect evaporative cooling (IEC) system with different recirculation air ratios. Three other cooling systems, including stand-alone Direct Evaporative Cooling (DEC), stand-alone M−cycle IEC, and conventional solid desiccant evaporative cooling system (SD-DEC), were also simulated and compared with the proposed system under various ambient conditions. These systems were assessed in terms of supply air temperature, indoor relative humidity ratio, water consumption rate, coefficient of performance (COP) and solar fraction in this study. A case study of the proposed system was carried out under two typical Australian climates, Darwin and Melbourne. The results indicated that the solar-assisted solid desiccant cooling system integrated with M−cycle IEC had the best cooling performance compared with the other three systems, particularly in hot and humid areas. When increasing the recirculation air ratios from 0% to 60%, a maximum reduction of 23.1% and 41.9% could be observed in the system’s supply air temperature and humidity ratio, respectively. The highest COP was 0.89 when the inlet air temperature was 30 °C, and the COP value would vary as the inlet air temperature and humidity ratio increased. However, a higher water consumption rate was also observed, 31.36% to 57.94% more water would be consumed. This indicates that it requires selecting a proper recirculation air ratio for different climates to achieve the best performance.

Experimental Study of Permeability Characteristics of Bamboo Betung Activated Carbon as Alternative Pad Material for Direct Evaporative Cooling System

The increased growth in the building sector, especially in big cities, has triggered an increase in the need for electrical energy for cooling systems, most of which use compressor-based cooling systems. Direct Evaporative Cooling (DEC) is evaporative that produces cooling by utilizing the latent heat of evaporation of water on the wet surface of the pad material. The pad material must be sufficiently porous to allow the free flow of air through it and must have a large enough wet surface area. This study used carbonized and activated bamboo Betung as a material for the DEC system. The research was conducted to obtain the permeability characteristics of the carbonized bamboo pad material at various temperatures of 400oC, 500oC 600oC, 700oC, and 800oC and then activated at a temperature of 600oC with a holding time of 60 minutes. Based on the results of the research on the permeability characteristics of bamboo Betung activated carbon material, which was carbonized at a temperature of 400oC and activated at a temperature of 600oC with a holding time of 60 minutes (ABR 400) had the highest permeability of 13.6 x 10-15 m2. Meanwhile, the lowest permeability was produced by bamboo Betung material which was carbonized at a temperature of 800oC and activated at an activation temperature of 600oC with a holding time of 60 minutes (ABR 800) which is only 0.56x10-15 m2.

Performance evaluation and parameter sensitivity analysis of a membrane-based evaporative cooler with built-in baffles

Evaporative cooling systems have attracted increasing attention for energy-efficient air conditioning applications. A hollow fiber membrane-based direct evaporative cooler (HFM-DEC) is proposed in this study. The selected membrane material can selectively allow only water vapor to penetrate, while preventing the passage of bacteria and fungi, thereby avoiding deterioration of indoor air quality. Compared with the conventional evaporative coolers with counter-flow and cross-flow arrangements, the proposed novel configuration performed better cooling ability by installing baffles in the air flow channel to enhance the air disturbance. The parameter sensitivity analysis was conducted on the HFM-DEC with built-in baffles by employing an experimentally validated numerical model. The orthogonal test method was used to study the influence of nine key parameters of the HFM-DEC on its wet-bulb effectiveness, coefficient of performance, and the cooling capacity. According to the optimized scheme, the HFM-DEC with a relatively optimal configuration was proposed. The cooling performance of this module was investigated under various inlet air conditions. The results showed that if the inlet air velocity was maintained within the range of 0.5–2 m/s, it was capable of achieving an optimal performance with the wet-bulb effectiveness of 70%-95%, the COP of 17–78, and the cooling capacity of 60–106 W, respectively, under diverse weather conditions. Correlations of Nusselt number and Sherwood number were developed by fitting the simulation results. The influence of Reynolds number on air stream characteristics was obtained based on the analysis of the velocity field, temperature field and concentration field of this module under varying operating conditions.

Experimental evaluation of energetic and exergetic enactment for exotic evaporative to expansion-type edifice-coolers

Evaporative cooling is a natural, environment-friendly, and economical method of air-conditioning involving minimal energy consumption. However, the wider dependency on the climatic condition, lower cooling capacity, lesser effectiveness, excess humidification, etc., limits the evaporative coolers' global acceptance. Therefore, multi-staging of evaporative coolers or hybridization with any conventional direct expansion system is recognised as a solution for building air-conditioning. Accordingly, a three-stage cooling test rig comprising indirect and direct evaporative coolers followed by a direct expansion system is indigenously developed and efficacy of seven single to multi/hybrid modes is experimentally evaluated. Rigorous experiments are conducted during the entire summer of Hyderabad, India, from April to July of 2019 by operating the test rig from 20th to 26th of each month from 8:00 AM to 8:00 PM with an interval of one hour. Based on the acquired experimental data, energy, exergy, heat transfer and environmental analyses are carried out. The three-stage cooling combination exhibits the highest wet-bulb effectiveness reaching a maximum of 300% with the lowest supply air temperature of 16 °C. Multi-staging provides an average sensible cooling load reduction ranging from 15.21% to 65.04% on the direct expansion cooling system. Moreover, the two-stage indirect-direct evaporative cooler exhibits excellent exergy efficiency with sufficient cooling capacity reaching 90%. The DEC-DX, IEC-DEC and IEC-DEC-DX cooling combinations exhibit superior SEER magnitudes over entire cooling season indicating effectiveness of evaporative pre-cooling.

Performance of The Direct Evaporative Cooler (DEC) Operating in A Hot and Humid Region of Sabah Malaysia

In the last decade, energy consumption for air conditioning applications has been dramatically rising because of the growing global population and increasing comfort demand. Consequently, direct evaporative cooling (DEC) technology is emerging as an alternative to vapour compression air conditioners due to its lower environmental impacts, less energy consumption, and lower operating costs. This paper aims to verify the experimental results of a direct evaporative cooling system operating under hot and humid climate conditions city of Sabah, Malaysia. The study's aim is to evaluate the efficiency of direct evaporators in hot, humid environments like Malaysia. Inlet and outlet temperatures, saturation efficiency, cooling capability, and feasibility index are all used to evaluate results. The cooling medium was a rectangular honeycomb cooling pad with a length of 34 cm, a width of 25 cm, and a thickness of 3.5 cm. The temperature and humidity during the analysis were between 31 and 35oC and 47.5 and 65.5%, respectively. The results showed that the air output temperature varied between 28.4°C and 31.7°C, while the cooling capacity between 0.29 kW and 0.64 kW as well as the saturation efficiency between 46% to 80% could be achieved. The result also shows that feasibility index between 19 to 24. Due to the high value of the feasibility index, this evaporative cooling does not work well in the territory of Malaysia. A direct evaporative cooler may be made to work in humid places like Malaysia by drying the air before the evaporative process using the desiccant dehumidification concept.

THE IMPACT OF VENTILATION RATE ON RADON CONCENTRATION INSIDE HIGH-RISE APARTMENT BUILDINGS.

Radon is the main pollutant of indoor air, being considered a primary cause of lung cancer, especially in non-smokers. In 2013, European legislation required the standardization of regulations on radon exposure in member states using EC Directive 59/2013 EURATOM. The directive establishes basic safety rules for protection against the dangers represented by the exposure to ionizing radiation. Directive 59/2013 mandates each European country to establish a national action plan to reduce the risks of lung cancer attributed to radon in the general population and exposed workers. Romania is a European country with almost 20 million citizens, with over half of population living in urban locations. Most urban buildings in Romania are high-rise structures (4-10 floors), having many residential units. In this paper, we present results of season-dependent measurements of radon concentration and ventilation rates in high-rise apartment buildings and show the influence of ventilation on indoor radon levels. Indoor radon concentrations varied between 70 and 168Bqm-3 in winter and 17-30Bqm-3 in summer, being higher than the respective outdoor concentrations by 2-5 times in winter and 1-4 times in summer. Ventilation rates varied with season and were influenced by meteorological conditions at the time of measurements. Findings indicate that levels of indoor radon concentration depend on ventilation rates of the unit, but also on building materials, wind speed around building, time of day (higher around noon) and season of the year (higher in the cold season when ventilation rate is lower).

Numerical analysis-based performance prediction in a direct evaporative cooler used for building cooling

In the present performance parameters is determined for the varied operating conditions using mathematical modelling. Outlet humidity ratio, Dry bulb temperature (DBT), cooling efficiency and cooling effect have been predicted by varying the air velocities, inlet DBT, inlet relative humidity (RH) and pad thickness for three different wettability of Celdek packing. Predicted results revealed that cooling effect, saturation efficiency, ΔDBT and humidity ratio are found to be increasing with the increase in pad thickness and wettability of the material. An increase in the inlet air flow rate and RH resulted in a decrease in ΔDBT, humidity ratio and cooling efficiency. The maximum performance of ΔDBT, ΔRH, saturation efficiency and cooling effects have been observed for Celdek 7090 and are equal to 6°C, 55%, 90% and 7000 Watts for the thickness of 0.3 m, wettability of 630 m2/m3. Wettability of 630 m2/m3 & thickness 0.3 m gave maximum performance.

Experimental investigation of an integrated absorption- solid desiccant air conditioning system

Separate handling of sensible and latent components of building loads can be an energy efficient approach compared to simultaneous management of both. This paper presents a detailed experimental analysis of an energy efficient air conditioning system using solid desiccant integrated with absorption system for separate building thermal load handling. The experimental system consists of silica-gel based solid desiccant for latent load handling, whereas the gas fired air-cooled NH3-H2O absorption chiller is used to handle sensible load of the space. A chilled water-cooling coil heat exchanger is installed on the process side of desiccant cooling system to integrate it with the absorption chiller. The performance of integrated absorption- solid desiccant system is compared with a standalone conventional desiccant air conditioning system with a direct evaporative cooler considering it as baseline system under wide range of operating conditions including air temperature, air humidity, and regeneration temperature. The comparative analysis is performed in terms of supply air temperature, cooling capacity, and coefficient of performance. The experimental results exhibit that supply air temperature of the integrated system is 15.2 °C compared to 24.6 °C achieved by conventional desiccant system. Moreover, COPth of the integrated system is also 50–55% higher than its counterpart and it is almost comparable with double-effect absorption chiller. It is concluded that the integrated system using separate load management approach is more efficient for HVAC applications.

Research and Application of Evaporative Cooling Ventilation and Salty Moisture Corrosion Prevention Technology for Steam Turbine House

This paper focus on Pakistan Hub coal-fired 2×660MW power project which located in the coast areas with high temperature and high salty moisture. The category of corrosivity of atmosphere in Pakistan Hub is C5. The high salty moisture will increase the corrosion of indoor equipment and structures in turbine house, which threaten the safe and stable operation of power plant. Direct evaporative cooling (DEC) technology is used to cool the centralized supply air for the turbine building. To prevent the salty moisture air being supplied into turbine building causes corrosion for indoor equipment and structures, the desalting moisture filter has been developed and combined with the evaporating cooling unit, which realized the large-scale engineering application. The efficiency of desalting moisture filter reaches more than 93% tested in Tongji University and VTT in Finland, under the condition of the design outdoor temperature of 38.9 °C in Karachi, the supply air temperature is 24.4 °C, which ensures the operating environments of working area and meeting the occupational hygiene requirements and anti-salt spray corrosion requirements.

Development and Characterization of a Miniaturized, Low-Cost Cross-Flow Direct Evaporative Cooler

Development and Characterization of a Miniaturized, Low-Cost Cross-Flow Direct Evaporative Cooler

Experimental Performance Evaluation of Date Palm Fibers for a Direct Evaporative Cooler Operating in Hot and Arid Climate

Experimental Performance Evaluation of Date Palm Fibers for a Direct Evaporative Cooler Operating in Hot and Arid Climate

Liquid desiccant systems for cooling applications in broilers farms in humid subtropical climates

This paper intends to numerically analyse the performance of liquid desiccant systems on the supply air conditions for closed poultry barns. A commercially available evaporative cooler for poultry barns was modified into a desiccant dehumidifier by circulating desiccant solutions of LiCl-H2O and CaCl2-H2O instead of water. Ambient air conditions for one of humid and subtropical climates were simulated based on an ∊-NTU effectiveness model for an externally cooled liquid desiccant dehumidifier. Also, a distinctive temperature-humidity index (THI) was implemented to study the environmental thermal conditions that the poultry were subjected to. Concerning the thermal comfort for broilers, the results show that conventional direct evaporative cooling systems are not feasible when the ambient air is near saturation. The THI values for ambient and direct evaporative cooler were positioned mainly in the severe heat stress region, with THI value in the range of 80 to 82, and most air outlet conditions were near saturation. The numerical results for the liquid desiccant systems show a consistent reduction in humidity ratio and air dry-bulb temperature. The assessment of air outlet temperature and humidity in terms of THI values was shifted out of the emergency and danger zone with a preference for LiCl solution.

Performance assessment of a desiccant air-conditioning system combined with dew-point indirect evaporative cooler and PV/T

In this study, a new solid desiccant air-conditioning system configuration integrated with direct and dew-point indirect evaporative coolers and water-cooled photovoltaic-thermal solar collectors (PV/T) is proposed and simulated for a building located in Adana, a humid and hot city on Mediterranean coast of Turkey. New multiple linear regression equations are developed for the performance of desiccant wheel and dew-point indirect evaporative cooler, which are the two crucial components of the air-conditioning system and used in hourly simulations. Building set temperature, exhaust air mixing ratio, suitable warm air source for preheating regeneration air and optimum connection strategy of PV/T collectors to each other are examined in detail. Hourly and daily thermal coefficient of performance (COPth), solar fraction, primary energy consumption and specific primary energy consumption are calculated to evaluate the energetic performance of the system. COPth of the system ranges from 0.28 to 0.40 during the day, with a daily COPth of 0.34. 69% of the thermal energy required to regenerate desiccant wheel can be generated by the PV/T water collectors.