Cooling Water Waste Research Articles

Research on the Operational Performance of Organic Rankine Cycle System for Waste Heat Recovery from Large Ship Main Engine

Based on the analysis of the waste heat distribution characteristics of a typical ship two-stroke low-speed main engine (model: MAN 8S65ME-C8.6HL, the specified maximum continuous rating SMCR: 21,840 kW) under different loads, two different types of organic Rankine cycle (ORC) systems, namely the basic system (BORC) and the preheated system(PORC), were constructed to recover the ship main engine’s exhaust gas waste heat and jacket cooling water waste heat. Using the thermodynamic simulation model of the system, the main performance indexes, including net output power of the two ORC systems were studied with the variation of seawater temperature and main engine load, and the annual ship fuel saving and annual carbon emission reduction generated by the two systems were compared and analyzed. It was found that the maximum net output power of the BORC system and PORC system were 445.3 kW and 491.3 kW, respectively, when the ship’s main engine load was 100%, and the outboard seawater temperature was 20 °C; the maximum thermal efficiency was 12.84% and 12.71%, respectively; under the annual operation, the fuel saving of BORC system and PORC system can be 456 tons and 510 tons, respectively, and the carbon emission reduction was 1416 tons and 1581 tons, respectively. The analysis found that the net output power of the PORC system is always greater than that of the BORC system. When the outboard seawater is lower, and the main engine load is more than 80%, the net output power difference between the PORC system and BORC system gradually expands, and the improvement of ORC system performance is more evident by adding a preheater. It can be concluded that when the ship was mainly operated in the sea area with low seawater temperature and the main engine was running under high load most of the time, selecting the PORC system to recover the waste heat of the main engine was more advantageous.

Energy saving for an air conditioning system applied in a thin-film-transistor liquid-crystal display (TFT LCD) high-tech fabrication plant (Fab)

Data collected from this research is used to calculate energy consumption of the thin-film-transistor liquid-crystal display (TFT LCD) air-conditioning system. These results are then used to determine how much energy can be saved and proposes to reduce the energy consumption of the chiller component of the air conditioning system. Analysis based on factory operation data collected in the past indicates that process machine operation accounts for 45% of total energy usage. In addition to the power consumption of the factory system, compressed dry air CDA accounted for 22% of the total energy consumption. The high temperature chiller accounted for 7% and ranks second, while third is FFU power consumption, accounting for 6%. When evaluating the feasibility of energy conservation, it is necessary to collect operating parameters and evaluate the operating efficiency of the equipment to identify potential changes to effect energy conservation. According to preliminary analysis of distribution and operation data, it is found that the current filter used in the fan filter frame (FFU) responsible for the clean room circulation is a traditional high-efficiency filter made of glass fiber. Glass fiber filters can be replaced with PTFE filters, offering potential energy savings associated with lower pressure drop. The factory does not add CDA cooling water waste heat recovery and utilization in the warm water system. After the addition of this recovery system, the cooling water temperature will increase by 0.6 °C and the estimated electric boiler energy saving is 1.86%.If the new generation high-efficiency chiller were installed, under typical operating conditions where the load is between 70% and 90%, annual efficiency is expected to be between 0.423 kW/RT and 0.412 kW/RT, which is expected to save 2.6% when compared with older generation chiller technology.; If two sets of the original chillers are replaced with one chiller in constant use and one in standby configuration, the annual efficiency is 0.4 kW/RT, saving 5.4%. Replacing a configuration of four sets with three in constant use and one in standby configuration, the annual efficiency is 0.388 kW/RT, saving 8.3%.

Cultivating photosynthetic microorganisms in cooling water waste and urban effluents as a strategy of water regeneration and valorization

ABSTRACT Contaminants from cooling water waste (CWW) generated by industries represent an environmental hazard if discharged into aquatic bodies and soil without treatment. Most treatment strategies are energy-demanding and costly; hence, low-cost and sustainable treatment alternative technologies are needed. The present study proposed cyanobacteria culture as a low-cost biological method to treat cooling water waste (CWW) while simultaneously producing carbohydrates. For this purpose, CWW from a cooling tower was evaluated in different dilutions with domestic wastewater (DW) (DW25% -CWW75%, DW50% -CWW50%, DW25% -CWW75%, DW100%, and CWW100%) (v/v). The CWW provided a high content of inorganic carbon and low content of N and P, which resulted in a high C/N ratio promoting a fast carbohydrate accumulation but low biomass production. In contrast, cultures with higher DW concentrations achieved similar results in 14 days. The best results were obtained with DW25% -CWW75%, achieving up to 52 ± 18% carbohydrate content on day 8, with the highest biomass concentration of 1.7 ± 0.12 g L−1 on day 14. This culture removed >94% of TAN, N-NO3 - and P-PO4 3-, and 84 ± 10.82% of COD. This strategy could be a promising approach to treating CWW and DW from the same industry and producing value-added products and bioenergy.

Cultivating microalgae in cooling water waste and urban effluents as a strategy of water regeneration and valorization

Cultivating microalgae in cooling water waste and urban effluents as a strategy of water regeneration and valorization

Simulation and Economic Research of Circulating Cooling Water Waste Heat and Water Resource Recovery System

Industrial circulating cooling water contains a large amount of low-quality energy, which is lost to the environment through cooling towers. It is of great significance and potential to recover the waste heat to improve energy-saving effects and economic efficiency. However, the effect of common water harvesting and energy saving devices is not significant. Heat pumps have been shown to be effective in improving low-quality heat energy in energy conversion systems, although there are not many applications of heat pump scenarios in engineering practice. Based on this, a recovery solution of circulating cooling water waste heat and water resource using lithium bromide absorption heat pump has been put forward. The energy-saving performance of the recovery system was simulated and analyzed using Aspen Plus V10.0 (Bedford, MA, USA) to explore the effects of the parameters of the working medium in evaporators, condensers, absorbers, generators, heat exchangers, etc., and the modelling results indicated that the evaporation pressure and temperature have a great influence on the system COP (coefficient of performance) and can raise the thermal economy of the system. The heat from driving steam and heating capacity both increased with the increase in generating temperature, while the increase in temperature difference between evaporation and condensation inhibits the COP of heat pump systems. Furthermore, economic analyses and comparisons of the recovery solutions were conducted and the recovery solution of circulating cooling water waste heat with heat pump had the best economic performance due to the annual income from the recovery of waste heat and water resource. The static payback period results indicate that the recovery solution from circulating cooling water waste heat with a heat pump has better economic performance than the scenario with a cooling tower. The waste heat recovery solution with a heat pump can improve the thermal economy of the system and has a great guiding significance for engineering practice.

Thermo-economic analysis and optimization of ICE-ORC systems based on a splitter regulation

The traditional Organic Rankine Cycle (ORC) system recovering waste heat from Internal Combustion Engine (ICE) ignores the low-grade thermal energy of jacket cooling water. In this paper, a new ICE-ORC configuration is proposed to maximize the ORC net power output for different ICE rated power outputs. The comparative analysis between the ICE-ORC system based on a splitter regulation and two traditional ICE-ORCs is presented with ten different working fluids. The computational results demonstrate whether it is necessary to recover jacket cooling water waste heat with different working fluids, and cascade utilization of exhaust gas and jacket water waste heat by splitter regulation is validated with different Caterpillar series of ICE. Moreover, using pentane as working fluid has the best performance which ORC power output is 556 kW for all the three different ICE-ORC bottoming cycles and ten working fluids, and the ICE-ORC bottoming cycle efficiency is increased by 17% compared with single ICE generator set. This research provides information to increase the efficiency and power output of ICE-ORC configuration modification and determines the direction of further improvement.

Estimation of cooling water activation in high-energy heavy ion medical accelerator

The estimation of air, material, and cooling water activation is essential for designing a robust nuclear safety protocol for high-energy heavy ion medical accelerators. Demineralized cooling water activation is simulated for the C-12 ion beam medical accelerator (synchrotron) with a maximum energy of 430 MeV/u. Three conservative scenarios are proposed for the estimation of demineralized cooling water activation. Simulations were performed by using a combination of MCNPX2.7.0 and VCINDER codes. Simulation parameters were optimized to match the volume of the cooling water in the accelerator system. The sums of the ratios of specific activities to unrestricted release limits were calculated for the three scenarios as a function of decay time. All activity concentrations are far less than the corresponding unrestricted release limits after a 1-day decay time because the sums of the ratios are all less than 1.0. Noticeable hazardous radioactive elements were found to be H-3, Be-7, and C-11 which have relatively long half-life times. Although hazardous radioactive elements with relatively short half-life times (within 10 min), such as N-13, O-14, and O-15, are also produced in large concentrations, there are no unrestricted release limits specified in the table issued by the National and International Radiation Protection Ordinances. The estimation of cooling water activation is useful for designing a nuclear safety protocol for high-energy heavy ion medical accelerator facilities. Specifically, the results suggest that the direct discharge of the cooling water waste into the environment (in case of an accident or the end of the life cycle of cooling water) must not be permitted. A separate reservoir for cooling water waste collection is recommended with a dedicated real-time measuring equipment to measure the concentrations of H-3, Be-7, C-11, N-13, O-14, and O-15 separately.

Development of a Small Thermoelectric Generators Prototype for Energy Harvesting from Low Temperature Waste Heat at Industrial Plant.

A 39-W thermoelectric generator prototype has been realized and then installed in industrial plant for on-line trials. The prototype was developed as an energy harvesting demonstrator using low temperature cooling water waste heat as energy source. The objective of the research program is to measure the actual performances of this kind of device working with industrial water below 90 °C, as hot source, and fresh water at a temperature of about 15 °C, as cold sink. The article shows the first results of the research program. It was verified, under the tested operative conditions, that the produced electric power exceeds the energy required to pump the water from the hot source and cold sink to the thermoelectric generator unit if they are located at a distance not exceeding 50 m and the electric energy conversion efficiency is 0.33%. It was calculated that increasing the distance of the hot source and cold sink to the thermoelectric generator unit to 100 m the produced electric energy equals the energy required for water pumping, while reducing the distance of the hot source and cold sink to zero meters the developed unit produces an electric energy conversion efficiency of 0.61%.

Electricity and Heat Production by Biomass

This paper describes a cogeneration plant using wood biomass as fuel. Forests cover 56% of the surface area in Slovenia, providing plenty of waste wood to be used as an energy source. Waste wood unsuitable for the lumber industry is ground into biomass of G50 size, whose chips are on average 3 - 5 cm and up to 8 cm. Biomass is dried in a drier to reduce its moisture content to 15%. Wood biomass gasification takes place in a gasifier. Carbon monoxide and hydrogen, gasification end products, are used as fuels for a boiler and two gas engines. The boiler heat is used for wood-drying purposes. The cogeneration plant uses a 1 MW Caterpillar generator set and a 0.45 MW MAN generator set. Cooling water waste heat of both gas engines and exhaust gases are used for heating the wood drier and the nearby residential area.

Performance of a Score-Stove with a Kerosene Burner and the Effect of Pressurization of the Working Fluid

Score-StoveTM a clean-burning cooking stove that also generates electricity was tested using a pressurized kerosene burner. The Score-Stove works on the principle of thermo-acoustics to gen- erate small-scale electricity. The device having hot-end, cold-end and regenerator acts in a way similar to a stirling cycle generating acoustic power, which is then converted to electricity using a linear actuator. It can supply small power for applications such as LED lighting, mobile phone charging and radios particularly in rural areas without grid electricity as well as improving house- hold air pollution. After assessing the needs of the rural communities through a survey, tea-stalls and small restaurants owners were identified as clients with the most potential of using the stove in Bangladesh. Bangladesh University of Engineering and Technology ((BUET) modified a Score- Stove to use both wood and a pressurized kerosene burner of a design that is widely used for cooking in rural areas of Bangladesh. The design was adapted to meet performance needs such as: heating rate, cooking efficiency, energy distribution, electric power generation, exhaust emissions and time taken to boil water using standardized water boiling tests. Performance was also compared with conventional (non-electrically generating) stoves that use a pressurized kerosene burn- er. The Score-Stove performance was then evaluated while increasing the pressure of the sealed working fluid (air in this case) from atmospheric to about 1.4 bar. The pressurization was found to almost double the power generation. An arrangement for utilizing cooling water waste heat was also devised in order to improve the thermal performance of the stove by 18%. Technical deficiencies are documented and recommendations for improvements and future research in order to obtain wider end-user acceptance are made.

Study on the Eco-Design of Utilization Scheme of the Cooling Water Waste Heat

Waste heat utilization reduces thermal pollution and fosters energy conservation. Based on the investigation and research work on potential usages of waste heat from cooling water, the preliminary study on the eco-design of comprehensive utilization scheme of waste heat was carried out, with the application of ecological engineering theory and philosophy of eco-design. The feasibility analysis showed that the industrial use and district heating of waste heat have better environmental and economic benefits. The evaluation indexes system was established based on the positioning of final result of the ecological design of cooling water waste heat utilization scheme for a nuclear power plant.

Bottoming organic Rankine cycle configurations to increase Internal Combustion Engines power output from cooling water waste heat recovery

This work is focused on waste heat recovery of jacket cooling water from Internal Combustion Engines (ICEs). Cooling water heat does not always find use due to its low temperature, typically around 90 °C, and usually is rejected to the ambient despite its high thermal power. An efficient way to take benefit from the ICE cooling water waste heat can be to increase the power output through suitable bottoming Organic Rankine Cycles (ORCs). Thereby, this work simulates six configurations using ten non flammable working fluids and evaluates their performances in efficiency, safety, cost and environmental terms. Results show that the Double Regenerative ORC using SES36 gets the maximum net efficiency of 7.15%, incrementing the ICE electrical efficiency up to 5.3%, although requires duplicating the number of main components and high turbine size. A more rigorous analysis, based on the system feasibility, shows that small improvements in the basic cycle provide similar gains compared to the most complex schemes proposed. So, the single Regenerative ORC using R236fa and the Reheat Regenerative ORC using R134a seem suitable cycles which provide a net efficiency of 6.55%, incrementing the ICE electrical efficiency up to 4.9%.

The Study of Cooling Water Waste Heat Recovery in Chemical Plant by Heat Pump System

A large number of cooling water exists in chemical plant, use water source heat pump and lithium bromide absorption heat pump system to achieve water cooling instead of cooling tower, at the same time, extract heat for building cooling and heating. Respectively introduced the summer cooling system and winter heating system, and a feasibility analysis was carried out. The conclusion is get: water source heat pump system and lithium bromide absorption heat pump system for cooling water waste heat recovery is certain feasibility; the environment optimization can be achieved in chemical plant, at the same time, energy conservation and emission reduction is realized.