Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle (original) (raw)
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ADVANCED COOLING TOWER CONCEPT BASED ON THE MAISOTSENKO‐CYCLE - AN EXERGETIC EVALUATION
International Journal of Energy for a Clean Environment, 2011
The Maisotsenko-Cycle (M-Cycle) is a complex process associated with humid air. Heat transfer and evaporative cooling occur in a unique indirect evaporative cooler, resulting in product temperatures that approach dew point temperature. The different applications of the M-Cycle contribute to effective energy savings. By enhancing cooling towers with the M-cycle it is possible to (a) cool water to temperatures approaching dew point temperature, and (b) reduce the pressure drop and the required fan power. An exergetic analysis identifies the real thermodynamic inefficiencies and the potential of improvement of energy conversion systems. This paper discusses the results obtained from a detailed exergetic analysis of the M-Cycle applied to a cooling tower. In the analysis physical and chemical exergies are considered and the physical exergies of all material streams are split into their thermal and mechanical parts. The paper concludes with a sensitivity analysis.
Overview of the Maisotsenko cycle – A way towards dew point evaporative cooling
The Maisotsenko Cycle (M-Cycle) is a thermodynamic conception which captures energy from the air by utilizing the psychrometric renewable energy available from the latent heat of water evaporating into the air. The cycle is well-known in the airconditioning (AC) field due to its potential of dew-point eva-porative cooling. However, its applicability has been recently expanded in several energy recovery applications. Therefore, the present study provides the overview of M-Cycle and its application in various heating, ventilation, and airconditioning (HVAC) systems; cooling systems; and gas turbine power cycles. Principle and features of the M-Cycle are discussed in comparison with conventional evaporative cooling, and consequently the thermodynamic limitation of the cycle is highlighted. It is reported that the standalone M-Cycle AC (MAC) system can achieve the AC load efficiently when the ambient air humidity is not so high regardless of ambient air temperature. Various modifications in MAC system design have been reviewed in order to investigate the M-Cycle applicability in humid regions. It is found that the hybrid, ejector, and desiccant based MAC systems enable a huge energy saving potential to achieve the sensible and latent load of AC in humid regions. Similarly, the overall system performance is significantly improved when the M-Cycle is utilized in cooling towers and evaporative condensers. Furthermore, the M-Cycle conception in gas turbine cycles has been realized recently in which the M-Cycle recuperator provides not only hot and humidified air for combustion but also recovers the heat from the turbine exhaust gases. The M-Cycle nature helps to provide the cooled air for turbine inlet air cooling and to control the pollution by reducing NO x formation during combustion. The study reviews three distinguished Maisotsenko gas turbine power cycles and their comparison with the conventional cycles, which shows the M-Cycle significance in power industry.
Maisotsenko cycle: technology overview and energy-saving potential in cooling systems
Energy and Emission Control Technologies, 2015
The present paper deals with an overview of Maisotsenko cycle (M-cycle). This cycle is an indirect evaporative cooling-based cycle, which utilizes a smart geometrical configuration for the air distribution. The achievement of this geometry is the high efficiency of the cycle, as it produces cold air of temperature lower than the wet-bulb ambient air temperature. As the energy source of this cooler is water rather than electricity, the usage of M-cycle-based coolers leads to significant energy saving, more than 80% in terms of electricity. The heat and mass exchanger is analyzed and described in detail, so the specifications of M-cycle will be clear and understandable. The operation of the standard configuration of M-cycle is studied thereafter and useful conclusions are carried out, about the efficiency and the energy consumption (electricity and water). Finally, the energy-saving potential is estimated in conventional cooling systems, in terms of electricity and capital cost, in order to evaluate the financial benefit of M-cycle application: the pay-back period is calculated equal to about 2.5 years (as the result of the replacement of conventional systems with M-cycle-based ones). The study is to be a useful tool to anyone interested in energy saving in buildings and in industrial plants, as the operating cost, which is strongly affected by the cooling demand, is significantly reduced by the application of M-cycle.
Feasibility study of Maisotsenko indirect evaporative air cooling cycle in Iran
This paper presents energy and exergy analysis of air cooling cycle based on novel Maisotsenko indirect evaporative cooling cycle. Maisotsenko cycle (M-cycle) provides desired cooling condition above the dew point and below the wet bulb temperature. In this study, based on average annual temperature, The Iran area is segmented into eleven climates. In energy analysis, wet-bulb and dew point effectiveness, cooling capacity rate and in exergy analysis, exergy input rate, exergy destruction rate, exergy loss, exergy efficiency, exergetic COP and entropy generation rate for Iran's weather conditions in the indicated climates are calculated. Moreover, a feasibility study based on water evaporation rate and Maisotsenko cycle was presented. Energy and exergy analysis results show that the fifth, sixth, seventh and eighth climates are quite compatible and Rasht, Sari, Ramsar and Ardabile cities are irreconcilable with the Maisotsenko cycle.
Exergy Analysis of Evaporative Cooling for Optimum Energy Consumption in Diverse Climate Conditions
In this paper, exergy of conditioned air, exergy efficiency, irreversibility, and entropy generation of common models of evaporative cooling have been investigated in five cities of Iran. Direct evaporative cooling (DEC), indirect evaporative cooling (IEC), and twostage IEC/DEC as the most popular methods of cooling have been modeled. Atmospheric conditions are considered as the dead state of each city. Exergy analyses of conditioned air are based on the output results of the theoretical modeling of evaporative cooling. Moreover, exergy balances of three cooling methods are derived. Thus, exergy destruction, reversible work, and entropy generatiom are calculated according to the exergy balances. The results obtained reveal that Bam, which is a hot city with medium relative humidity (24%RH), has the best exergy efficiency of direct evaporative cooling. The highest exergy efficiency of twostage indirect/direct evaporative cooling belongs to Kerman. Kerman with the lowest dry-bulb temperature has medium relative humidity (24%RH). In addition, total output exergy of air in Yazd is more than other cities. Yazd is a hot-dried city with rather low relative humidity (19.5%RH).
Exergy analysis of evaporative cooling to select the optimum system in diverse climates
Energy, 2012
In this paper, an exergy analysis is applied to indicate the exergy efficiency and irreversibility of common models of evaporative cooling. Exergy analysis of conditioned air are based on the results of experimental investigations on the direct, indirect, and two-stage indirect/direct evaporative cooling for six cities in Iran, each having various weather conditions. For this purpose, exergy balances of three cooling methods are derived. The results obtained reveal that for a comprehensive efficiency analysis, both the first and second law of thermodynamics should be considered. Furthermore, the direct evaporative coolers work best in temperate and dry climate with estimated exergy efficiency of 20%. The indirect evaporative coolers are more efficient in hot and dry climate with approximate exergy efficiency of 55%. The indirect/ direct evaporative coolers are better choice for hot and semi-humid climate with exergy efficiency of about 62%.
Performance study of the cross-flow Maisotsenko cycle in humid climate conditions
International Communications in Heat and Mass Transfer, 2020
This paper presents a first numerical analysis of the cross-flow Maisotsenko cycle (M-Cycle) below dew-point evaporative cooler for humid climates with model including the water vapor condensation phenomenon. Proposed solution allows to cool ambient air below its dew-point temperature, by utilizing cooling energy in air extracted from the building, due to that it can be used as effective pre-cooling solution for traditional systems. Proposed unit has significant advantage over traditional counter and cross-flow units operating in heat recovery mode, hence it is almost insensitive on temperature of exhaust air. This is caused by effective pre-cooling of the exhaust air in its initial part. Operation in humid climates using cold extracted air results in condensation occurrence in the primary air channels, and hence partial dehumidification of the primary airflow (which allows to cool the air before its dew-point temperature). The Maisotsenko cycle exchanger used to recover heat in the airconditioning system is compared with Maisotsenko exchanger that operates only on the ambient airflow and does not allow to recover heat from the exhaust airflow from a conditioned space. Achieved results showed that M-Cycle below dew-point air cooler can operate more effectively in humid climates than traditional cross-flow Maisotsenko cycle exchanger.
Engineering Applications of Computational Fluid Mechanics , 2020
In this work, a numerical and experimental study is performed to evaluate the affecting variables on energy efficiency of a novel regenerative evaporative cooler utilizing dew-point indirect evaporative cooling. For first time, an investigation is experimentally and numerically carried out to study the effects of the channel number on important parameters such as product temperature and humidity ratio. Investigations are carried out for five configurations with various channel numbers. The comparison of the numerical and experimental results is obtained and well accuracy observed. For the five studied configurations, the results show that with an increase in the number of channels, the outlet temperature decreases. For an inlet air flow rate of 100–600m3/h, the cooled outlet flow temperature changes to the range of 23.4–30.7°C, 19.7–28.3°C, 18–26.4°C, 17.2–25°C and 16.6–23.8°C. For the configurations with finned channels, the percentage of increase in produced air temperature reaches 11.5% for HMX B, 18.6% for HMX C, 23.4% for HMX D and 26.9% for HMX E, as compared with HMX A.
A Review on Potential of Indirect Evaporative Cooling System
One of the world's most energy consuming sector is heating, ventilation and air conditioning. A lot of energy is consumed by traditional cooling systems based on the conventional vapour compression refrigeration cycle. The VCR system which contains refrigerants in circuits produced a harmful effect on environment and also dangerous to human life if leakages occur. These factors were mainly responsible for the development of evaporative coolers. In direct evaporative cooling system, it will give adequate temperature drop of air with increase in humidity which is not desirable for human health. So for overcoming these difficulties, indirect evaporative cooling system will be used for air coolers in which heat mass exchanger is used. To get higher temperature drop and wet bulb effectiveness above 100%, Scientist Valeriy Maisotsenko developed Maisotsenko cycle. The aim of our study is to find the best alternative of existing conventional cooling systems.