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We consider the problem of designing a capacity control method for induced draft cooling towers that can be operated in different modes (bypass, showering, ventilation) to meet the heat rejection requirement. Recent efforts provide an adequate solution using mixed integer model predictive controller, however the combinatorial formulation of the problem might result in prohibitively large computation time limiting its applicability in real time scenarios. To this end, we propose a computationally efficient capacity control method based on a two stage optimization approach for handling the mode selection and optimal fan speed of the cooling tower. The solution to the first stage optimization program provides optimal fan speed which is then utilized by the second stage optimization program to determine the best operational mode of the cooling tower. An algorithm is proposed which relies on the integration of autonomous dynamics of bypass and showering mode and the relationship between showering and ventilation mode to efficiently solve the two stage optimization problem. Numerical simulations are provided to validate the performance of the proposed capacity control method.

Any electromechanical system can experience vibrations due to electromagnetic or mechanical factors and the fact negatively affects the performance and durability of the system. Modern vibration diagnostics systems are used for early prediction of malfunctions in electromechanical equipment. They are sometimes economically impractical. It is proposed to study the instantaneous electrical power of the engine to assess the mechanical vibrations of the electromechanical complex. A geared drive of a cooling tower fan is taken as an electromechanical complex, as mechanical vibrations arise there caused by the imbalance of the shaft. By means of mathematical modeling, studies of the impact of gear drive mechanical vibrations on the electric instantaneous power of an induction drive motor were carried out. The spectral analysis was carried out to identify the effect of vibrations.

This paper describes a demonstrative example of an industrial desalination and denitrification system based on renewable energy resources for a sustainable and efficient irrigation. A demo wastewater treatment plant is located in the ArcoSur Mar Menor facilities (Cartagena, Spain) aiming to maximize the reclaimed water recovery from the brine and to remove the relevant pollutants. This demo plant is an industrial combination of biological, membrane separation and thermal technologies that allow us to obtain reclaimed water for irrigation and a dried salt with potential market value. The plant consists of an autonomous renewable energy off-grid solution to cover all energy demand of the brine treatment. Life Desirows European Project also combines different evaporation technologies and includes a cooling tower based on the evaporation of brackish water and consecutive condensation of the generated humid air, mostly at ambient pressure. The project is expected to reduce considerable the energy demand and emissions. This solution is easily extensive toward other areas with similar water scarcity problems, which currently affects at least 10.4% of the EU territory and 14.3% of the EU population, mainly in Southern Europe.

This work deals with the study of water and air distribution irregularity in an industrial natural draft cooling tower (NDCT). Statistical histograms of water and air flow distribution in the NDCT are made, a significant degree of water and air irregularity has been established and a general criterion for the dimensionless water and air distribution has been introduced. We have analyzed the flows’ distribution law and have found that the statistical data of water and air flow in natural draft cooling towers adhere to the normal distribution law. The distribution functions of the dimensionless of water concentration and air velocity are obtained. A technical and economic calculation of the irregularity flows influence on the thermal power plant fuel consumption has been carried out. The knowledge about the law of the water and air concentration distribution is necessary for more accurate calculations in the cooling towers design and operation.

The water conservation bodies are reciting the use of grey-water to alleviate water consumption. The condensed water is a by-product of air conditioning that could be harvested at no extra cost and energy and its water quality is always good enough for direct application. The mineral-free condensed water is an ideal dilution to lower down the concentration of mineral-laden system water. The water losses mainly come from the water evaporation; while the bleed-off water for dilution is determined by the cycle of concentration (CoC). The higher CoC is, the lesser bleed-off volume will be. The conductivity sensing controller controls the level of Total Dissolved Solid (TDS) by dosing chemical agents interlocking with an auto bleed-off valve. Taking industrial standard 2,500ppm and make-up fresh water (130ppm), CoC is 19, bleed-off water are partially replenished by supplementary condensed water (60ppm). The reduction of bleed-off water is 70% that further increases to 85 % with the routine cooling tower cleansing water discharged. The water scale hinders the cooling towers' heat dissipations to the atmosphere and diminishes the condensers' heat transfer between the refrigerant and cooling water. For every 1°C condensing temperature rises, chiller's COP would decrease as 12% more energy consumed. The cooling tower cleansing and water quality control would abate scale formation, which are practical and maintainable. The condenser tube cleansing would improve condenser approach temperature that could enhance heat transfer between the refrigerant and condensing leaving water. The COP of the chiller unit was improved by 3.17%, once after annual condenser tube cleansing.

The study focuses on the water saving technology for external cooling system of DC transmission converter station equipment, a water saving design applicable to external cooling system of such key equipment cooled by water as converter valve and transformer in the converter station of the conventional/flexible DC transmission project. Current external cooling method for converter valve equipment in the converter station mostly combines the closed-circuit cooling tower and spray cooling. This method, however, has the disadvantages of, for example, high water consumption and large quantity of blowdown. In view of this, this paper proposes a water saving technology by sewage recycling through spray treatment system based on two-stage reverse osmosis. In this technology, the water in the converter station can be recycled, thus achieving the purpose of water saving and blowdown reduction. For the transformer cooled by external cooling with water, this paper provides an optimized design of common configuration in which the external cooling systems of converter valve and transformer share the same spray pool and spray treatment equipment. This design will not only save water resources, but also facilitate the operation, maintenance and comprehensive management of converter station. It is thus in accord with the green development philosophy of converter station.

Firstly, the hydraulic models of the main components of the circulating cooling water system and the pipe network system were established, and solved using Newton's iterative method. Furthermore, considering the influence of the external environment and the temperature of the circulating water on the operating characteristics of the system, the thermodynamic models of the cooling tower and plate heat exchanger were established, and they were linked with the hydraulic model of the pipe network system to obtain the overall model of the circulating cooling water system and the rationality of the modeling was verified. For the specific circulating cooling water system, the adaptive differential evolution algorithm is used to identify the mechanism parameters in the overall model of the pipe network system to improve the accuracy of the model. Simulation results show the effectiveness of the method used.

Currently, a pressing issue is a research and development of cooling technological equipment with considering water management, including efficient and energy-saving technologies with water-protecting schemes. The authors have proposed a new design of a cooling tower for circulating water with a developed filling unit, consisting of inclined-corrugated contact elements. The design of the filling unit and the operation principle of the cooling tower were described. The paper represents an analysis of the volumetric heat and mass transfer coefficients of inclined-corrugated contact elements in comparison with analogs widely used in the industry. A criteria relationship was obtained, allowing for an engineering assessment of the efficiency of the filling unit. The dependences of the volumetric heat and mass transfer coefficients on the average air velocity at the various wetting densities have been plotted. The high cooling capacity of the inclined-corrugated contact elements due to the uniform distribution of gas-liquid flows in the cross-section of the cooling tower has been proven.

The power output of solar panels shows an inverse relation with increasing its operating temperature and that affects largely for countries like Sri Lanka, which are situated near the equator. Possible cooling techniques, which are aligned with the Sri Lankan context, were studied by referring to past research and available systems. Rear side forced water-cooling with a thermal collector which is known as the hybrid system was identified as the most feasible technique by considering economic and environmental factors. The theoretical model was developed to estimate the design parameters of the thermal collector and cooling performance. The number of ten thermal collector design configurations were modeled and analyzed the cooling performance using ANSYS fluent simulations. The best design configuration was identified based on heat transfer and manufacturing capability. A prototype of the selected design was manufactured to investigate the cooling performance experimentally. The experimental setup was developed using two 100 Watts solar panels and a small scale cooling tower. Both power and panel temperature variation were analyzed both numerically and experimentally. The numerical model was validated using experimental results and design parameters were optimized as it gives a better cooling performance. Both numerical and experimental analysis shows that integrating a rear side cooling system would increase both electrical and thermal efficiency by 65%. The electrical efficiency improvement is 2.5 % and electrical power generation is increased by 28% compared to the panel without cooling. Considering the cost benefits and the environmental conditions of Sri Lanka, using a solar PV hybrid system is a feasible option to enhance both electrical and thermal gains.

The demand from the grid requires a flexible operation approach by the generating stations. It requires the generator to vary load as per the requirements of the grid which changes rapidly. One of the parameters crucial for power generation is condenser vacuum. The operator needs to keep a constant watch on condenser pressure for safe and reliable generation. At low load, to save Auxiliary Power Consumption (APC) operator takes several steps and makes a trade off with condenser vacuum. In this context, it becomes essential to have a tool which can assimilate changes in the system and predict condenser vacuum. Parameters on which Condenser Vacuum largely depends upon, is the Cooling Water (CW) inlet temperature, CW Outlet Temperature, CW flow to Condenser, Exhaust Hood Temperature and instant power generated by the unit. A guiding tool can be handy for the operator to switch off CW pumps, Cooling Tower (CT) fans and other auxiliaries which affect Condenser Vacuum in order to save APC. An advance prediction tool can also assist the operator to analyze any unwanted changes in the operating parameters of the unit. In this paper we will be using several regression algorithms on sample plant data to train our predictive model and to adjudge the prediction given by each algorithm for condenser vacuum. The data used for training and testing of model is obtained from the 210 MW Russian Turbine based Thermal Power Station.

Significant research efforts and resources are being put in improving the performance and efficiency of a vertical plate packing cooling tower during their industrial application. Limited success has been achieved as more research effort is still geared towards designing a vertical plate packing cooling tower with more acceptable operating efficiency during usage. This study focused on experimental investigation of cooling tower performance of a vertical plate packing cooling tower. The tower is filled with a packed column of 150mm x 150mm x600mm high in transparent acrylic with 100m2/m3 plate packing. The experiment was performed with three different airflow velocities, 2.74m3/s, 1.95m3/s and 0.6m3/s to test the system performance and efficiency during application. It was also revealed that the cooling tower efficiency is higher at the high airflow velocity, which is 30.5% and lower at a low airflow velocity, which was 12.4%. It can be concluded that the investigated design of the cooling tower is not performing well as the efficiency is lower than 50%.

With the development of better computational powered metering infrastructure, there is an increasing interest in using machine learning methods for non-intrusive load monitoring. In this paper, variations of input-output data model and long-short term memory, a deep learning layer, are implemented and discussed for energy disaggregation of a chiller plant system of a commercial building for energy monitoring purposes. Then, error analysis is carried out for the multi-mode, multi-state cooling tower operation. The opportunities and challenges of towards energy monitoring are then briefly discussed. Unlike NILM residential buildings applications for on-off equipment status determination, NILM for industrial system focuses on estimating the power level of the disaggregated components due to high cost of sub-metering.

Wind tower has been used as traditional Arabic architectural element to create passive ventilation in buildings for human comfort in hot and arid regions. Greenhouse agriculture has been a profitable technology despite the large energy and water need. Integrating these technologies will result in substantial energy and water saving. Sensible cooling is attempted first in the greenhouse. The time evolution of the temperature variation of the flowing air and temperature of conduit walls along the height of the tower and at the greenhouse exit are studied. Parameters like tower height, made-off materials, entry temperature, and wind velocity are considered in the quest to reach to lowest temperature at the greenhouse exit. A high-fidelity model is developed governed by the non-isothermal Navier-Stokes flow in conjugated heat with the conduit material in unsteady and turbulent flow regime. The continuity, momentum, energy, and turbulent scalars are solved simultaneously and results are compared/validated against the first principle of convective-sensible heat for conduit temperature. Results reveal that additional height enable more cooling energy storage, however this cooling energy is non-sustainable and depletes in a relatively short time over several minutes. This suggests utilization of very high specific heat materials or integration of trans-evaporative cooling. The latter is simulated and results are favorable and shows to bring the needed cooling to the greenhouse.

This paper deals with the study of circulating water cooling processes in evaporative cooling towers with various filler units, widely used at TPPs and in chemical, petrochemical, oil & gas processing industries. The process flow diagram and design of cooling tower with closed cooling water are proposed in this paper by the authors that allow to reduce significantly the amount of chemical reagents to be used. The authors studied the design, consisting of developed jet-film contact elements, as a cooling tower filler unit. The proposed checker fillings can provide a large surface area of phase contact with a small number of irrigation points, a minimum percentage of liquid drops entrainment by the gas flow and a low hydraulic resistance. Based on the Lewis analogy, an equation to calculate the volumetric heat transfer coefficient, taking into account the ratio of mass flow rates of air and water, as well as the irrigation density, was obtained. It was found that the volumetric heat transfer coefficient increases with an increase in the irrigation density due to the turbulence of flowing down liquid film. The comparative results of calculations of volumetric heat transfer coefficient and the Merkel number for different cooling tower filler units are shown in this paper. It is proved that the proposed jet-film contact elements have the greatest cooling capacity among the studied checker fillings.

Recirculating cooling water networks (CWN) consists of three main components: heat exchanger networks (HEN), recirculation system and cooling tower (CT). In current practice, the cooling water (CW) is circulated without reuse via HEN in parallel configuration to provide cooling duties for hot process streams and returns to CT with high flow rate and low temperature. Therefore, there is a decrease in the performance of the CT.In this paper, the Demand-Composite Analysis (DCA) based on Pinch technology is developed for CW reuse and to address energy efficiency issues in CWN for retrofit design problem. This technique is an analytical approach requiring no graphical procedures can targets simultaneously, prior the detailed network design, the minimum flow rate and maximum temperature of waste cooling water (WCW) from HEN to CT. Under these conditions, the effectiveness of CT becomes high and CT that eliminates more heat.The application of DCA requires that cooling requirements be converted to their equivalent in terms of sources and demands The Demand-Composite Curve (DCC) is a graphical representation generated from DCA to understand the targeting philosophy. A case study is treated to illustrate the practicability of this approach. For this case, the effectiveness of CT is enhanced from 56.9% to 64.1%.

The project work concentrates on the development of a summer air conditioning system for the Mechanical Engineering wing in the College of Engineering building at King Faisal University, Kingdom of Saudi Arabia. A complete air conditioning system consists of the basic air conditioning system coupled with the refrigeration system and its associated pumping and cooling tower systems. In this paper, the development of the basic air conditioning system is considered. Therein, sensible and latent heat loads from various sources were evaluated in the mechanical engineering wing and a basic air conditioning system was developed. Based on mixing conditions, five different cases, were considered in this project. As a part of air conditioning system, the basic design of the cooling coil was developed. The cooling coil is a cross flow heat exchanger and it is assumed to be operating in counter cross flow configuration. Performance charts were developed for the counter cross flow heat exchanger in terms of meaningful dimensionless parameters. These charts will certainly help heat exchanger designers in developing the most cost efficient heat exchanger.

Data centers are important players in the energy infrastructure. Aiming at addressing environmental challenges, large data centers such as Facebook, Google, Yahoo, etc., are increasing share of green power in their daily energy consumption. Such trends drive research into new directions, e.g. sustainable data centers. The research often relies on expressive models that provides sufficient details however practical to re-use and expand There is a lack of available data center models that capture dynamics of the facility from the CPU to the cooling tower. It is a challenge to develop a model that allows to describe complete data center of any scale including its connection to the grid. This paper proposes such a model building on existing work. The challenge was to put the pieces of data center together and describe dynamics of each element so that interdependences between components and parameters are captured correctly and in sufficient details. The proposed model was used in the project "Data center microgrid integration" and proven to be adequate and important to support such study.

During extremely hot summer days, air conditioners are known as major electricity consumers in residential, commercial and industrial sectors. Moreover, high energy requirement of multiple-chiller plants may cause an interconnected power grid be faced with annual on-peak electrical demand, load-generation mismatch, voltage collapse and catastrophic wide area blackout. Therefore, this paper presents a day-ahead economic dispatch model for co-optimization of water cooled multiple chiller systems and ice storage unit aiming to minimize total power consumption of cooling towers, pumps, chillers, ice making and melting processes. In addition, the refrigeration capacities of chillers and ice storage unit and the cooling load-generation balance criterion are considered as optimization constraints. On/off states and partial load ratios of chillers and ice storage unit, power consumptions of pumps/cooling towers/chillers/ice making mode/ice melting process, temperature of cooling tower outlet water, mass flow rate of cooled water, mass flow rate of water flowing in and out of cooling tower, time and amount of generation and consumption of ice, and state of charge of ice storage tank at each hour are considered as decision variables. Simulations are conducted on a benchmark system with two 550 refrigeration ton (RT) units, four 1000 RT chillers, 2000 RT ice storage capacity, and different cooling load levels over a 24-hour time horizon using generalized algebraic mathematical modeling system (GAMS) software.

This paper presents results of a study on effects of cooling tower performance to energy consumption of a water cooled chiller system of an office building in Jakarta the capital city of Indonesia. The building was recorded as a less efficient office building with energy use intensity reaching 271 kWh m-2, year-1. The study was conducted by running a water cooled chiller with alternately two different cooling towers of similar specified capacity. Energy and temperature performances of the cooling towers were tested and evaluated. Performance parameters of the chiller that rejected heat to each cooling tower were evaluated, and then the chiller performances involving its energy use were calculated. It was found that one cooling tower had less air flow rate. Its efficiency was only 38% which was much lower than the efficiency of another cooling tower of 61%. Performance of the chiller to be operated with lower efficiency cooling tower, decreased by 5.5% and power consumption increased by 4.1%. The result of this study also showed that cooling tower performance was an important parameter that could make an office building less-energy efficient.

The goal of this research is to estimate prospects of using natural gas absorption system as a conditioning system for industrial premises in summer time. In this paper we explored and validated the main tendencies in organization if microclimate at the industrial enterprises. The number of problems related with integration of absorption cooling machines to the industrial facility was listed. It was proposed to examine the issue of application of local low power absorption system for conditioning. In this work we carried out thermal design of absorption system. Based of calculation results we carried out heat engineering calculations of closed cooling tower, which satisfies the requirements for heat diversion during exploitation of this absorption system. We carried out economic design and based on results analysis we draw a conclusion about practicability of implementation of proposed solution to the industrial facilities.

Pathogens can thrive in the damp environment of an evaporator coil or cooling tower in an air conditioner. To ameliorate this problem, an automatic fluid-delivery prototype is built to mix three constituent parts of a cleaner in prescribed amounts then spray the solution onto an evaporator coil. Flow rates, system geometry, and chemical compatibilities are all considered. The prototype is part of the Internet of Things (IoT) and costs $1,000. The machine is designed for a two-ton air conditioner but is expandable for larger systems.

Non-condensable gas (NCG) is a part of geothermal fluid that affects geothermal power plant performance. Two scenarios were proposed to extract NCG out of condenser; i.e two-stage steam jet ejector (SJE) intercondenser plus one-stage SJE after condenser (three-stage SJE) and hybrid (combination of two-stage SJE intercondenser and vacuum pump). Both scenarios were optimized by the installation of Variable Frequency Drive (VFD) to hot well pump and cooling tower fan, respectively. Each scenario was analyzed to the wet bulb temperature (WBT) fluctuation. This study modeled the data of Darajat Geothermal Power Plant unit III on load 100% (110 MW) and computed it using Engineering Equation Solver commercial version 9.430. The consideration of both scenarios was analyzed by Specific Steam Consumption net. The result of this study indicated that hybrid system can save 1.11% energy compared with three-stage SJE. It is also found that hybrid system had a possibility to optimize by VFD installation when WBT in 15.5 °C up to 19.5 °C. The highest energy saving was obtained 1.03% compared to constant L/G, on WBT 19.5 °C, where L/G denotes the ratio of inlet water mass flow rate to cooling air inside cooling tower.

PID is by far the most dominating method for cooling-water pump control in refrigeration station systems. However, PID may cause oscillations when load changes. If the parameter of PID controller is not tuned appropriately, overshoots will occur and adjustment time becomes longer [2]. But fractional PID controller has better dynamic performance than traditional PID controller. Fractional order PID controller has stronger robustness, and can better ensure system’s stability when interference is added to the system [1]. This paper mainly studies the fractional PID controller for control of temperature of supply cooling-water in central air conditioning system. The data model of the cooling tower is parameterized with the help of MATLAB curve fitting toolbox. Based on a large number of experimental data, the transfer function model of the controlled object is established. The simulation results show that fractional PID controller can make the speed of cooling-water pump respond to the changing load more quickly and overshoot is smaller compared with traditional PID controller.

The paper discusses the importance of using smart metering systems for monitoring the performance of natural draft wet cooling towers. The performance of this type of cooling towers (which are commonly used in thermal power plants) is influenced by their sizing, by the warm water coming from the condenser and by the uncontrollable, but forecastable, weather conditions. As the temperature of the cooled water has a key influence on the operation and efficiency of the entire power plant, it is important to carefully watch the performance of the cooling tower. The cooling performance indicators are presented, along with the functions of the smart metering system of a cooling tower. As an example, a simulation model of a cogeneration power plant was used, to emphasize the variation of the performance indicators due to the change of the input conditions (regarding certain ambient conditions and the entering warm water).

To optimize the structure of the circulating water system and ventilation system for cooling water tower, making full use of recycled water into mechanical energy to work, transforming into the wind turbine power; system optimization can decrease scale deposition, and the tower fan power consumption, to achieve the optimization of energy saving. Improve the circulating water treatment equipment, reduce the scale, improve the heat transfer coefficient, and realize the protection of the implementation of the case, structural optimization. In this paper, the traditional water tower optimization design improvement on today's used cooling tower is a kind of transformation using, which saves the current structure of the current, and also reduces the operation cost of building saving energy equipment has a certain role.

In this paper, the effect of crosswind on triple natural draft dry cooling towers is studied and analyzed. Concerning this area, many researches have concentrated on one cooling tower. This research focuses on the mutual effects of the adjacent towers' performance, and also makes a comparison between the efficiency of the three cooling towers in windy and no-wind conditions. Three dimensional governing equations with standard k-e model for turbulence are solved using finite volume method. In modeling the crosswind condition, at first radiator-type windbreakers with usual uniform distribution, and then radiator-type windbreakers with heterogeneous distribution of water are used for each cooling tower. Finally, the water outlet temperature of the radiators' cooling towers are analyzed, and the total heat rejections at different conditions are compared. Numerical results show that radiator-type windbreakers with heterogeneous distribution of water can substantially improve cooling efficiency more than uniform regime. It should be mentioned that a complete grid study is done to achieve a grid-independent solution.

The presented analysis carried out for the safety assessment of the Passive Residual Heat Removal System of secondary side (PRS), one of the Severe Accident Mitigating System of K-2/K-3 Nuclear power plants. Preliminary analysis of the PRS is carried out using computer code MELCOR, which is a thermal hydraulic code that models the progression of severe accidents in light water nuclear power plants. The system was analyzed under SBO without the main feed-water, auxiliary feed-water and the safety injection systems. The system is activated after the SBO and failure of auxiliary feed-water pumps and the turbine driven pumps by opening the isolation valves and closing the main steam isolation valve to avoid the steam loss. Three trains of PRS are modeled and connected with secondary side of each Steam Generators along with a make-up tank, each trains is connected with the same cooling tower (Heat Sink). The system can maintain the reactor in safe condition for 72 hours, if it is actuated before the large loss of primary coolant inventory or fuel damage in the core. The three independent trains for each steam generator are consider for heat removal of secondary side. If one of the train is considered unavailable that will lead to fuel failure and RPV failure within 72 hours. Although the failure time increases in comparison to the SBO without the PRS. The reactor remains in safe conditions if the PRS system operate at or above 80% of its design thermal load removing capability. The safety assessment was made with and without using this severe accident countermeasure introduced in K-2/K-3 NPP.

In this work, application of the Golden Section Search Method (GSSM) is illustrated to inversely retrieve the controlling parameter meeting a desired performance requirement in an induced draft cooling tower. Merkel number is an important performance parameter because it involves various parameters such as global heat and mass transfer coefficient, water flow rate, dimensions (interfacial area per unit volume) and range within itself. At first, experiments have been performed to get accurate correlations for Merkel number against the controlling parameter that is required to be estimated, which is the air mass flow rate. Then, an inverse optimization technique involving GSSM has been used to estimate the required air flow rate in order to satisfy a given performance parameter. It is found from the present study that the controlling parameter estimated using GSSM yields a very good reconstruction of the Merkel number.

Chilled-water plants with multiple chillers are the backbone of ventilation and air conditioning (VAC) systems for commercial buildings. Optimal operation and sequencing of such plant has great impact on building energy efficiency. Large variations in equipment characteristics and operating conditions make it difficult and expensive to obtain plant models required by model-based control/optimization approaches. For a variable primary flow (VPF) chilled-water plant with parallel chillers, a model-free optimization and sequencing strategy is proposed to maximize energy efficiency in real time, based on a penalty-function based multivariate extremum seeking control (ESC). The ESC takes the total power consumption (chiller compressors + cooling tower fan + condenser water pumps + input-saturation penalty) as feedback, while tower fan airflow, condenser water flows and evaporator leaving chilled-water temperature setpoint as manipulative inputs. A band-pass filter array replaces the high-pass filter in the standard ESC to reduce the cross-channel interference. The chiller sequencing is enabled with input saturation related signals. Simulation study is performed under several testing conditions using a Modelica based dynamic simulation model of a chilled-water plant with two parallel chillers, one cooling tower, one air-handling unit and one zone. Simulation results validate the effectiveness of the proposed strategy with significant energy saving demonstrated.

Traditionally, the equipment of central air-conditioning system include refrigeration circulating water system, cooling water system, cooling tower fan system, etc. The design of their capacity is based on the building's maximum cooling, heat load or fresh air. And the motor is fixed for a long time in power frequency state run at full speed, no matter how user load change. However, the user loads is low in the most time, so it caused great waste of energy. This paper research a method of Fuzzy PID on the control of frozen pump frequency control, which will change the frequency of frozen pump based on the variation of user's load and achieve the goal of energy saving.

In this paper a mathematical model has been developed of a unit for the desalination sea water based on humidification-dehumidification process with solar energy input. Mass and energy balances as well as thermodynamic analysis of the cooling tower and the condenser that are the main constituents of the unit are used in this mathematical model. A set of non linear equations is obtained then solved to obtain the key parameters needed in the design of the unit. The results obtained from the theoretical model are in very good agreement with those obtained experimentally.

This study surpassed traditional energy-saving ideas to propose a multi-core concept implementation of an energy-saving optimization model. The model allowed systems to match the optimum status, and used multi-core concept implementation for frequency conversions according to different weather conditions and air conditioning load changes, allowing systems to run at their optimum states for ideal energy-saving operations. This study probed into the power and energy consumption behavior models of chiller and system devices, focusing on how systems could reach optimization. The energy-saving effects were determined from the operating results and practical electric meter pricing. The annual saved energy costs were as high as USD $3820k per year, which included a cooling water pump energy-saving benefit of USD $1920k and a cooling tower and chilled water pump energy-saving benefit of USD $1900k. Annual CO2 emissions were reduced by 32,870 tons, which was the equivalent of the amount of CO2 absorbed by 2,728,460 trees.

Thermoelectric has gained attention for its clean energy generation. It has the potential of converting heat from renewable energy into direct current electricity which will replace our dependency on fossil fuels. This paper presents thermoelectric power generation system which consists of cooling tower that provides direct water cooling and solar thermal collector that provides high heat source on thermoelectric modules. Eight (8) thermoelectric modules connected in series with 40mm × 40mm × 3.5mm in size were sandwich between the absorber plate from parabolic trough collector and cooling water inside the square tube. Cooling tower thermal performance was evaluated using SolidWorks Flow Simulation software and experimental validation in steady-state and transient analysis. Experiment results show that the cooling tower has a thermal capability of lowering 100°C heated water to 28°C cold water at 2.51/min. A temperature difference of 97°C across the thermoelectric module was achieved with 28°C maintained on the cold side and 125°C on the hot side. It generated up to 21Watts at 12.7Volts. Thermoelectric technology has a significant potential for renewable and sustainable power generation especially when integrated with cooling towers for medium scale and large scale thermoelectric power generation.

Air-cooled Data Centers absorb heat in central room air conditioners or air handlers and most commonly reject the heat through cooling towers to ambient air. The energy efficiency of the overall cooling system is determined by the energy efficiency of its components, its thermodynamic design and layout, and the protocol for its control, operation and its operational set points. The current work is part of an effort to develop a comprehensive analysis tool for thermodynamic modeling and analysis of such cooling systems. The tool, called Villanova Thermodynamic Analysis of Systems (VTAS), allows integration of sophisticated thermodynamic models of data center components into system layouts and then allows simulation of both steady state and transient system behavior from chip to cooling tower. This paper reports on the development of a steady-state model for a constant flow rate, counterflow mechanical draft cooling tower using a finite difference method and the subsequent synthesis of data from this model into a fast reduced order model developed using an Artificial Neural Network (ANN) approach. The outlet water temperature, moist air thermodynamic state, heat transfer, and exergy destruction are computed. By comparing the heat transfer and the exergy destruction from this model, an optimum range for the air flow rate was found for a set of inlet conditions based on the minimization of exergy destruction. An ANN model was developed using data generated from the detailed model. The ANN model is fast and accurate and is easily integrated into a system simulation code such as VTAS.

By studying a VAV air conditioning system, and using a large number of experimental data and theoretical analysis, a optimal control strategy of cooling tower water temperature was found and proposed, based on change rate of chillers and power equipment energy consumption.

According to the disequilibrium bar stability problems of the mature application cooling tower, under the precondition of satisfying the cooling tower strength and stability, to optimize design cooling tower rods, making the structure more reasonable, thus reduced the weight and the cost. The research work provides theoretical basis for autonomous design of the cooling tower, the findings have high practical application value.

The aim of this study is to report the performance as well as the gained experiences and lessons learned with two different solar cooling systems. The first cooling system is an integrated cooling plant having both free cooling system and solar powered single-effect lithium bromide-water absorption chiller in operation since August 2002. A floor space of 270 m2 is air-conditioned by the plant. The plant includes 35.17 kW cooling absorption chiller, vacuum tube collectors' aperture area of 108m2, hot water storage capacity of 6.8 m3, cold water storage capacity of 1.5m3 and a 134 kW cooling tower. For this solar driven cooling plant, the performance data show that free cooling in some cooling months can be up to 70% while it is about 25% during the 5 years period of the plant operation. Moreover, for sunny clear sky days with equal incident solar radiation, the daily solar heat fraction used to drive the chiller ranged from 0.33 to 0.41; collectors' field average efficiency ranged from 0.352 to 0.492 and chiller COP varies from 0.37 to 0.81, respectively. The monthly average value of solar heat fraction varies from 31.1% up to 100% with five years average value of about 60%. The monthly average collectors' field efficiency value varies from 34.1% up 41.8% and the five-year average value amounts about 28.3%. The second solar driven cooling system is a steam jet ejector chiller (SJEC) driven by parabolic trough collector. The chiller has a capacity of one kW cooling. The experiments show that the particular characteristics of a SJEC with the strong influence of the condenser cooling water temperature and evaporator temperature on the system coefficient of performance. The coefficient of performance reaches high values in part load and at good re-cooling conditions, so that the mean efficiency is clearly higher than the nominal efficiency of the system. A first calculation of profitability leads to specific cold cost of 0.62 €/kWh in Germany and 0.15 €/kWh in Egypt.

Under certain conditions, condenser pressure can be considered as back pressure of the steam turbine, which has great influence on the unit power. Based on the back pressure calculation model, influence on back pressure variation by adjusting circulating water flow is discussed in this paper. The model is developed from mechanism analysis of the condenser and cooling tower. Results show that cooling water inlet temperature is an important parameter during the back pressure calculation. Changing the unit output by adjusting circulating cooling water flow of the cold-end system has different effects on the unit output increment and decrement.

This paper presents an extremum seeking control (ESC) scheme for energy efficient operation of chilled-water system, and Modelica based dynamic simulation models for demonstrating the effectiveness of the proposed control strategy. The simulated plant consists of a water-cooled screw chiller and a mechanical-draft counter-flow wet cooling tower. The ESC scheme takes the total power consumption of chiller compressor and tower fan as feedback, and uses the fan speed setting as control input. The inner-loop controllers for the chiller operation include two PI control loops for regulating the evaporator superheat and the chilled water temperature. Simulation was conducted for different scenarios. The simulation results demonstrated the effectiveness of the proposed ESC strategy, and the potential for energy saving is also evaluated. Also investigated is the ESC windup issue caused by the limitation of the fan's maximum operation speed. A back-calculation anti-windup ESC scheme is applied and its effectiveness is validated by simulation results.

the main factors which influence the recirculation under cooling tower are analyzed theoretically, the experimental model tests are also carried out to discuss the affect extent of factors to recirculation under cooling tower, the results can provide theoretical direction in decreasing and avoiding recirculation under cooling tower

In this paper, in view of the present situation of fault monitoring of the cooling tower fan operation. New cooling tower fan fault monitoring system is designed, which is based on a set of PC (as the host computer), the microcontroller (as the next crew to the new RS485 bus) and a new monitoring method. This paper mainly introduces the composition of the monitoring system and the monitoring principle of the new cooling tower fan blade shaft and the fault of blade. The method of monitoring improves the reliability of fault monitoring fan and reduces the fatal crashes of fan, which has good application value.

This paper describes three cooling tower evaluation indicators. By using three different evaluation methods which includes the contrast method of cooling water, cooling capability and efficiency coefficient, the performance of cooling towers is evaluated. Compare and analyze the evaluation results, we find they are not consistent. This paper analyzes the causes of different results, summarizes the application scopes and limitations of each evaluation indicator and puts forward some suggestions for the cooling tower evaluation.

This paper presents the performance of Air Handling Unit (AHU) system at Engineering Complex (formally S&T Complex), University Teknologi MARA Shah Alam Selangor. HVAC system of Engineering Complex consists of chillers, compressors, motors, pumps, cooling tower, ice cell, air handling unit (AHU) and also fan coil unit (FCU). This study focus on AHU system and describes the result of the operation of the AHU system. The data obtained were observed and analyzed to measure the performance by comparing the quality of the supply air, the return air of the AHU and room temperature in certain duration. A good operation and maintenance plan of AHU is the main success to minimize energy consumption. Due to that, the recommended guideline for AHU performance has been introduced to provide thermal comfort with energy efficiency at Engineering Complex, UiTM.

A CFD (Computational Fluid Dynamics) software (STAR-CD) was employed to simulate the performance of the NNP's (nuclear power plant's) cooling tower with drift injection in neutral atmosphere condition. With the N-S equations were closed with k-e equations, a mathematical mode could be established for simulating the flow in cooling tower. After simulating drift diffusion and rise in a normal size and simple condition, the relation of drift diffusion and rise to air velocity was analyzed. The result was analyzed and compared with Gauss Plume model and Hanna model, which proved the feasibility of this method. Also, some insufficiency about the method and improving suggestions were given in this paper.

A wind tunnel experiment for the effect of the cooling tower in an inland nuclear power plant on flow and dispersion of radioactive plume was introduced in paper. The model scale is 1:1500. Measurements of mean flow, turbulence characteristics and wake structure with different orientations of cooling tower and other buildings were made by using an X-array hot wire probe. The effects of the cooling tower and drift on dispersion of radioactive substances from the stack were investigated through tracer experiments. The results show that dispersion in near field is significantly enhanced due to the cooling towers and other tall buildings and the determinate effect of the drift released from the cooling towers on dispersion of pollutants from the stack was found. In general, the effects of cooling tower and its drift on the radioactive plume dispersion obviously depends on the height of release as well as the relative position of stack with cooling towers, especially significant for the case of the cooling tower parallel to stack along wind direction. Moreover, the wind tunnel experiment is a very important and effective tool to investigate micro-scale turbulent dispersion.

Owing to the high value of indoor heat gain in winter, the equipment rooms in an office building of Shanghai adopt air-conditioning system for cooling all the year around. For the actual demand of cooling load is low in winter, the equipments are often regulated by operating staff to increase the cooling load in order to ensure steady operation of the chillers. The scheme is determined by field research that utilizing free cold source, namely outdoor fresh air, to fulfil the cooling demands in intermediate season and winter of the equipment rooms which need cooling all year round. An improved IAQ will be obtained due to mechanical ventilation by using filtering devices of summer air duct system. Owing to reducing the year running time of related equipments such as chillers, chilled water pumps, cooling water pumps, cooling tower and so on, a large amount of air-conditioning energy consumption can be saved. On the basis of BIN parameters of Shanghai and the switch temperature defined in the paper, the energy consumption saved by free cold source and the operation consumption of air-conditioning are calculated respectively. The results show that the quantity of standard coal and electricity saved in a year are 703∼795tce and 1.74×106∼1.97×106kWh. Then the net total cost economized in first year is 1.39×106∼1.54×106RMB. Not considering bank interest rate and price fluctuation, the investment return cycle is less than two months. Therefore, the reconstruction scheme is feasible and economical. In addition, this scheme can also be applied to the comfort air conditioned rooms especially to the room with the requirement of cooling all the year round.