An Advanced Evaporative Condenser Through the Maisotsenko Cycle (original) (raw)
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International Journal of Heat and Mass Transfer, 2015
This paper investigates a mathematical simulation of the heat and mass transfer in the two different Maisotsenko Cycle (M-Cycle) heat and mass exchangers used for the indirect evaporative cooling in different air-conditioning systems. A two-dimensional heat and mass transfer model is developed to perform the thermal calculations of the indirect evaporative cooling process, thus quantifying the overall heat exchangers' performance. The mathematical model was validated against the experimental data. Numerical simulations reveal many unique features of the considered units, enabling an accurate prediction of their performance. Results of the model allow for comparison of the two types of heat exchangers in different applications for air conditioning systems in order to obtain optimal efficiency.
Using Evaporative Cooling Methods for Improving Performance of an Air-cooled Condenser
UJME-Universal Journal of Mechanical Engineering - Horizon Research Publishing, 2015
In areas with very hot weather conditions (50 to 60℃), the temperature and pressure of the air-conditioning condenser are increased considerably. This causes a decrease in the cooling capacity of the cycle and also causes an increase in the power consumption due to increased pressure ratio. In this work, an experimental and theoretical investigation has been done to improve the evaporator outlet fluid temperature through enhancing condenser performance. For this purpose, several modifications on the refrigeration system have been developed and tested to solve this hot weather problem. The air-side modifications include adding Spray Water above condenser (SW), wet Pad before condenser (Pad), and water Vapor Nozzle in the condenser air flow (VN). The refrigerant-side modification includes adding a pair of Heat Exchangers (HE) for exchanging heat between condenser exit and evaporator exit by using water-antifreeze mixture as a working fluid. A Water-Refrigerant(W-R) evaporator has been designed, manufactured, and compared with original Air-Refrigerant(A-R) evaporator performance. All air and refrigerant-side modifications have been investigated using both types of evaporators. The results indicate that the (SW) modification for enhancing condenser performance is the best method for COP improvement. The COP of (SW) system is found to increase at rate of (44.5 %) and (102.1%) as compared to system without modifications for (A-R) and (W-R) evaporators respectively. The outlet cooling temperature from evaporator has been found to reduce by about (30.3%) for (A-R) evaporator and (23.6%) for (W-R) evaporator. However, (HE+Pad) modification has been found as the best method for improving air side Nusselt number of condenser with an increase of about (4.7) times that of system without modifications. Ten new Nusselt number correlations have been predicted for each type of modifications under investigation by using both Engineering Equation Solver (EES) software and the experimental data. Cost-Benefit analysis in terms of life cycle cost, net present value, cost-benefit ratio, and payback period have been conducted. From the analysis, it can be concluded that using (SW) system will save a significant amount of energy with a payback period of less than five years.
International Journal of Energy for a Clean Environment, 2011
porative cooling process, thus quantifying overall heat exchanger performance. This mathematical model accounts for many unique features of the cross-flow heat exchanger, enabling an accurate prediction of performance. Results of the model show high efficiency gains that are sensitive to various inlet conditions and allow for estimation of optimum operating conditions, including suitable climatic zones for the proposed unit.
Performance assessment of an evaporative cooling-assisted window air conditioner
2011
Substantial growth in refrigeration and air-conditioning industry has made a significant impact on net energy consumption. Condenser pressure is one of the critical parameters in the energy-efficient operation of refrigeration and air-conditioning systems. A novel system is developed to use the condensate, available at the cooling coil, for condenser cooling of a window air-conditioner unit by employing evaporative cooling. Performance testing of the system has shown 13% savings in energy and up to 18% enhancement in coefficient of performance. The maximum benefit of the evaporative cooling cycle over the basic cycle was found to be in the region of moderate climatic conditions.
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.
Application Potential of the M-Cycle Exchanger to Air Conditioning Systems in Poland
DEStech Transactions on Environment, Energy and Earth Sciences
In the article the performance of the advanced indirect evaporative air cooler has been investigated. The application of the heat and mass exchanger in an air conditioning systems have been analyzed according to the typical climatic conditions in Poland. The considered indirect evaporative air cooler is based on the cross-flow heat and mass exchanger model with the Maisotsenko cycle (M-Cycle). The main conclusion is that an application of heat and mass exchanger with the M-Cycle to the typical air conditioning systems to the typical climatic conditions in Poland is characterized by the high cooling efficiency.
A Study on an Eco-friendly and High-performance Cooling System using Evapotranspiration March 2014
2014
According to International Energy Agency, buildings contribute nearly about 40 % total world energy consumption. Most of the consumption is used during their operational phase, especially for air conditioning, which causes peak-load in electricity demand in summer. Urban heat island recently has become a big issue for human's lives. Tokyo temperature has increased about 3.5 o C in the past one hundred years, while global temperature increases about 0.7 o C. Recognizing that heat released from outdoor unit of the air conditioning is one of the causes of heat island in the city, the objective of the study is to create a cooling system that does not exhaust heat to the environment. From the thermodynamic viewpoint, temperature is free from energy conservation. As the leaves of trees, they can keep the temperature or even make the air cooler while absorbing solar insolation, by evapo-transpiration. Learning from that phenomenon, an airconditioning system that not only cools the indoor space but also can create comfortable space outdoor by using evapo-transpiration is proposed in this study. With the fact that latent heat of water vaporization gives high potential of cooling capacity, e.g., 1 g water evaporation in 1 second can absorb about 2.43 kW heat at a temperature of 30 o C, it is expected that exhaust air from outdoor unit can reach to wet-bulb temperature, which is lower than that of ambient or drybulb temperature by 7 o C at dry-bulb temperature of 30 o C and the relative humidity of 50 %. Evapo-transpiration is applied to the condenser in the outdoor unit of the air conditioning system. Proposed condenser is copper-tubing covered by porous ceramics with tiny open holes, which can automatically spread water
Energy, 2014
In this paper a novel cross-flow HMX (heat and mass exchanger) utilizing the M-cycle (Maisotsenko cycle) for dew point indirect evaporative cooling has been tested for the performance evaluation in terms of thermal effectiveness and specific cooling capacity under various ambient and operational conditions. Additionally, the operational performance of the investigated HMX was examined on the base of developed model. The obtained results from the model prediction have been compared with the experimental data. The positive results of this validation indicated that the proposed model may be successfully used for prediction of operational performance of the investigated HMX. The analysis presented in this paper further demonstrates attractiveness and high efficiency of the novel M-cycle HMX used for indirect evaporative cooling in air conditioning units.
Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle
International Journal of Refrigeration, 2011
This study presents energy and exergy analyses and sustainability assessment of the novel evaporative air cooling system based on Maisotsenko cycle which allows the product fluid to be cooled in to a dew point temperature of the incoming air. In the energy analysis, Maisotsenko cycle's wet-bulb and dew point effectiveness, COP and primary energy ratio rates are calculated. Exergy analysis of the system is then carried out for six reference temperatures ranging from 0 C to 23.88 C as the incoming air (surrounding) temperature. The specific flow exergy, exergy input, exergy output, exergy destruction, exergy loss, exergy efficiency, exergetic COP, primary exergy ratio and entropy generation rates are determined for various cases. Furthermore, sustainability assessment is obtained using sustainability index method. As a result, maximum exergy efficiency is found to be 19.14% for a reference temperature of 23.88 C where the optimum operation takes place.