Absorption Lithium-bromide Chiller Research Articles

Innovative approaches and modified criteria to improve a thermodynamic efficiency of trigeneration plants

Trigeneration plants (TGP) desired for combined production of electricity, heat and refrigeration are highly flexible to follow current loading. But their highest efficiency might be possible only when heat production coincides with its consumption, which is generally impossible in traditional TGP with applying the absorption lithium-bromide chiller (ACh) converting the heat, released from combustion engine in the form of hot water, into refrigeration. Usually, the excessive heat of hot water, not consumed by ACh, is removed to the atmosphere through emergency radiator. However, the well-known methods of TGP efficiency assessment do not consider those heat losses and give the overestimated magnitudes of efficiency for conventional TGP with ACh. The application of booster ejector chiller (ECh), as an example, for utilization of the residual waste heat, remained from ACh and evaluated about 25%, has been proposed to produce supplementary refrigeration for cooling cyclic air of driving combustion engine to increase its electrical efficiency by 3-4 %. In the case of using the supplementary refrigeration for technological or other needs the heat efficiency of TGP will increase to about 0.43 against 0.37 for typical TGP with ACh as example. The new modified criteria to assess a real efficiency of conventional TGP, based on ACh, are proposed which enable to reveal the way of its improvement through minimizing the heat waste. Such combined two-stage waste heat recovery system of TGP can be considered as the alternative to the use of back-up gas boiler to pick up the waste heat potential for conversion by ACh to meet increased refrigeration needs.

Thermo-economic analysis, energy modeling and reconstructing of components of a single effect solar–absorption lithium bromide chiller for energy performance enhancement

This research includes a thermodynamic analysis of a solar absorption chiller due to design temperatures and pressures. Integration of solar energy and absorption chiller in low capacities is done by: static relations (including point-to-point system behavior variations) ruling absorption chillers, calculating the amount of required heat for the generator of the chiller and how it is supplied with, coding and determining optimal chiller coefficient of performance (COP) in Engineering Equation Solver (EES) software, evaluating the affecting factors on the COP by system analysis method. According to the system analysis of a combined solar-chiller system, the best COP is determined to be 0.77; which is a technically acceptable amount in small-size chillers. Also, the computational model for the economic evaluation of energy and energy-saving from receiving solar heat by using a suitable collector shows a 9-year payback period (considering the subsidized price: 0.01$ (2,500 Rails) per cubic meter of natural gas) and a 2-year payback period (considering FOB price equals 0.16$ per cubic meter natural gas). Therefore, it is proven that the economic feasibility of integrating absorption chillers and solar energy is affected by the price of energy carriers in real or subsidiary form and the bank interest rate.

Monitoring the efficiency of cooling air at the inlet of gas engine in integrated energy system

The fuel efficiency of gas engines is effected by the temperature of intake air at the suction of turbocharger. The data on dependence of fuel consumption and engine electric power on the intake air temperature were monitored for Jenbacher gas engine JMS 420 GS-N.LC to evaluate its influence. A waste heat of engine is rejected for heating water to the temperature of about 90??. The heat received is used in absorption lithium-bromide chiller to produce a cold in the form of chilled water. A cooling capacity of absorption chiller firstly is spent for technological needs and then for feeding the central air conditioner for cooling the ambient air incoming the engine room, from where the air is sucked by the engine turbocharger. The monitoring data revealed the reserves to enhance the efficiency of traditional cooling system of intake air by absorption chiller through deeper cooling. This concept can be realized in two ways: by addition cooling a chilled water from absorption chiller to about 5-7?? for feeding engine intake air cooler or by two-stage cooling with precooling ambient air by chilled water from adsorption chiller, in the first stage and subsequent deep cooling air to the temperatures 7-10?? in the second stage of intake air cooler by using a refrigerant as a coolant. In both cases the ejector chiller could be applied as the most simple in design.

Enhancing the exhaust heat recovery in integrated energy plant

The efficiency of exhaust heat recovery in typical integrated energy plant on the base of reciprocating gas engines with absorption lithium-bromide chiller for combined electricity, heat and refrigeration supply of the factory "Sаndorа"–"PepsiCо Ukraine" is analyzed. The reserves of decreasing the heat exhausted into atmosphere are revealed on the base of monitoring data and their realization through conversion into refrigeration for cooling the engine cyclic air is proposed. Some scheme decisions of improved and innovative exhaust heat recovery systems providing deep heat conversing into refrigeration for engine cyclic air cooling are developeded.

Innovative Turbine Intake Air Cooling Systems and Their Rational Designing

The efficiency of cooling ambient air at the inlet of gas turbines in temperate climatic conditions was analyzed and reserves for its enhancing through deep cooling were revealed. A method of logical analysis of the actual operation efficiency of turbine intake air cooling systems in real varying environment, supplemented by the simplest numerical simulation was used to synthesize new solutions. As a result, a novel trend in engine intake air cooling to 7 or 10 °C in temperate climatic conditions by two-stage cooling in chillers of combined type, providing an annual fuel saving of practically 50%, surpasses its value gained due to traditional air cooling to about 15 °C in absorption lithium-bromide chiller of a simple cycle, and is proposed. On analyzing the actual efficiency of turbine intake air cooling system, the current changes in thermal loads on the system in response to varying ambient air parameters were taken into account and annual fuel reduction was considered to be a primary criterion, as an example. The improved methodology of the engine intake air cooling system designing based on the annual effect due to cooling was developed. It involves determining the optimal value of cooling capacity, providing the minimum system sizes at maximum rate of annual effect increment, and its rational value, providing a close to maximum annual effect without system oversizing at the second maximum rate of annual effect increment within the range beyond the first maximum rate. The rational value of design cooling capacity provides practically the maximum annual fuel saving but with the sizes of cooling systems reduced by 15 to 20% due to the correspondingly reduced design cooling capacity of the systems as compared with their values defined by traditional designing focused to cover current peaked short-term thermal loads. The optimal value of cooling capacity providing the minimum sizes of cooling system is very reasonable for applying the energy saving technologies, for instance, based on the thermal storage with accumulating excessive (not consumed) cooling capacities at lowered current thermal loads to cover the peak loads. The application of developed methodology enables revealing the thermal potential for enhancing the efficiency of any combustion engine (gas turbines and engines, internal combustion engines, etc.).

ВИКОРИСТАННЯ НАДЛИШКУ ХОЛОДОПРОДУКТИВНОСТІ ХОЛОДИЛЬНИХ МАШИН ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ

The processes of the gas turbine inlet air cooling by exhaust heat conversion chillers, which utilizing the gas turbine exhaust gas heat, converting it into cold were analyzed. The use of two-stage air cooling has been investigated: to a temperature of 15°C – in an absorption lithium-bromide chiller and below to a temperature of 10°C – in an ejector chiller as stages of a two-stage absorption-ejector chiller. To simulate air cooling processes, the program "Guentner Product Calculator", one of the leading manufacturers of heat exchangers "Guentner", was used. The possibility of using the accumulated excess refrigeration capacity of a combined absorption-ejector chiller, which is formed at reduced current heat loads on air coolers at the gas turbine inlet, to cover the refrigeration capacity deficit arising at increased heat loads due to high ambient air temperatures has been investigated. The refrigeration capacity required to the gas turbine inlet air cooling was compared to an excess refrigeration capacity which excess of the current heat load. The considered air cooling system provides pre-cooling of air at the gas turbine inlet by using the excess refrigeration capacity of the absorption-ejector chiller, accumulated in the cold accumulator, to provide the required refrigeration capacity of the air pre-cooling booster stage. The simulation results proved the expediency of the gas turbine inlet air cooling using the accumulated excess refrigeration capacity of the combined absorption-ejector chiller. The proposed solution reduces by about 50% the design refrigeration capacity and, accordingly, the cost of the installed absorption lithium-bromide chiller, which acts as a high-temperature stage for cooling the ambient air at the gas turbine inlet.

ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТД ХОЛОДИЛЬНИМИ МАШИНАМИ ШЛЯХОМ АКУМУЛЯЦІЇ ХОЛОДУ

The efficiency of air cooling at the inlet of gas turbine engines by exhaust heat conversion chiller, which transforms the GTE exhaust gases heat into cold, under variable climatic operating conditions, has been investigated. Considered is the use of a combined absorption-ejector exhaust heat conversion chiller with a step-by-step principle of air cooling at the gas turbine engines inlet: preliminary down to 15°C – by an absorption lithium-bromide chiller (ACh), which is used as a high-temperature air cooling stage, and further cooling down to 10°C – by a refrigerant ejector chiller (ECh) as a low-temperature cooling stage. Reserves have been identified for reducing the design (installed) refrigeration capacity of chillers by accumulating excess cold at reduced current heat loads with its use at increased heat loads. In this case, the design (installed) refrigeration capacity of chillers was determined by two methods: the first – based on the close to the maximum reduction in annual fuel consumption, the second – according to the maximum rate of increase in the reduction in annual fuel consumption. A scheme of the air cooling system at the gas turbine engines inlet using the refrigeration capacity reserve of the ACh, which provides preliminary cooling of the ambient air at the gas turbine engines inlet, in the booster stage, using the ACh accumulated excess refrigeration capacity has been proposed. The ACh excess refrigerating capacity, which is formed at decreased heat loads on the air coolers at the gas turbine engines inlet, is accumulated in the cold accumulator and is used at increased heat loads. The simulation results show the advisability of using the air cooling system at the gas turbine engine inlet with using the ACh accumulated excess refrigeration capacity, which allows reducing the ACh design (installed) refrigeration capacity by approximately 40%.

ОХОЛОДЖЕННЯ НАДДУВНОГО ПОВІТРЯ ГОЛОВНОГО СУДНОВОГО ДВИГУНА АБСОРБЦІЙНОЮ БРОМИСТОЛІТІЄВОЮ ХОЛОДИЛЬНОЮ МАШИНОЮ В ЕКВАТОРІАЛЬНИХ ШИРОТАХ

The efficiency of cooling the scavenge air of the main low-speed engine of the transport vessel during operation in the equatorial tropical latitudes is analyzed. The peculiarity of the tropical climate is the high relative humidity of the air at the same time its high temperatures and temperatures of seawater. The cooling of the scavenge air with an absorption lithium bromide chiller by transforming the scavenge air heat into the cold was investigated. With this, the potentially possible minimum temperature of the cooled air was determined considering the temperature of the cold water (coolant) from the absorption lithium bromide chiller and the temperature differences in the heat exchangers of the intermediate water circuit of cooling. Absorption lithium bromide chillers are characterized by high efficiency of transformation of waste heat into cold - high coefficients of performance. Circuit-design solution of three-stage cooling system of scavenging air of ship's main engine - in high-temperature (cogeneration) stage using the extracted heat of scavenging air to get cold with absorption chiller and traditional stage for cooling scavenge air by seawater and low-temperature cooling stage by absorption chiller. The effect of deeper cooling of the scavenge air was determined in comparison with the cooling of the scavenge air with seawater, taking into account the changing climatic conditions during the route of the vessel. It is shown that due to the high efficiency of heat transformation in absorption chillers (high coefficients of performance 0.7…0.8), there is a significant amount of excess heat of scavenging air over the heat required to cool it to 22 °C, which reaches almost half of the available scavenge air heat on the Shanghai-Singapore-Shanghai route. This reveals the possibility of additional cooling the inlet of the turbocharger of the engine with the achieving almost double fuel economy due to the cooling of all cycle air of the low-speed engine, including the air at the inlet.

ПОРІВНЯННЯ ХАРАКТЕРИСТИК ГЛИБОКОГО ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТУ ДЛЯ РІЗНОГО ТИПУ КЛІМАТУ

The efficiency of deep air cooling at the inlet of gas turbine units has been investigated for changed climatic conditions of operation during the month. For air cooling, the use of waste heat recovery chiller has been considered, which transform the heat of exhaust gases of gas turbine units into the cold. The efficiency of air cooling at the inlet of gas turbine units to different temperatures has been analysed: to 15°C – an absorption lithium-bromide chiller, which is used as the first pre-cooling stage of ambient air and down to 10°C – a combined absorption-ejector chiller, with ejector refrigerant chiller as the second stage of air cooling.The air cooling efficiency is estimated for different climatic conditions: a temperate climate on the example of Odessa (Ukraine) and a subtropical climate for Guangzhou (China). The subtropical climate peculiarity of Guangzhou is the high relative humidity of the air, respectively, and its moisture contents at the same time its high temperatures. As an indicator, when evaluating the efficiency of air cooling at the inlet of gas turbine units to 15°C in an absorption lithium-bromide chiller and deep cooling of air to 10°C in a combined absorption-ejector chiller, the specific fuel consumption reduced has been used. In this case, the needs for specific production of refrigeration capacity and specific capacity of cooling towers for cooling waste heat recovery chillers when cooling air to different temperatures are compared. It is shown that, through extremely different thermal and humidity parameters of ambient air, its cooling at the inlet of gas turbine units to 10ºС for the climatic conditions of Ukraine provides the current decrease in specific fuel consumption due to deeper cooling of the air at the inlet of the GTU in 1.6 ... 1.7 times compared with cooling to 15ºС, and for climatic conditions of the PRC - 1.4 ... 1.45 times. However, it should be noted that a deeper cooling of the air at the inlet of the gas turbine unit to a temperature of 10°C in a combined absorption-ejector chiller compared to its traditional cooling to 15°C in an absorption bromine-lithium chiller requires an increase in the required specific amount of cold by 1.7 ... 2, 0 times and the required specific capacity of cooling towers for cooling chillers by 2.6 ... 3.0 times for the climatic conditions of Ukraine, while for China - 1.25 ... 1.3 and 1.5 ... 1.6 times, respectively.

ОЦІНКА ЕФЕКТИВНОСТІ ГЛИБОКОГО ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТУ ТЕПЛОВИКОРИСТОВУЮЧИМИ ХОЛОДИЛЬНИМИ МАШИНАМИ

Significant fluctuations in the current temperature and relative humidity of the ambient air lead to significant changes in the heat load on the air cooling system at the inlet of the gas turbine unit, which urgently poses the problem of choosing their design heat load, as well as evaluating the efficiency of the air cooling system for a certain period of time. The efficiency of deep air cooling at the inlet of gas turbine units was studied with a change during July 2015–2018 for climatic conditions of operation at the compressor station Krasnopolie, Dnepropetrovsk region (Ukraine). For air cooling, the use of a waste heat recovery chiller, which transforms the heat of exhaust gases of gas turbine units into the cold, has been proposed. The efficiency of air cooling at the inlet of gas turbine units for different temperatures has been analyzed: down to 15 °C – an absorption lithium-bromide chiller, which is used as the first high-temperature stage for pre-cooling of ambient air, and down to 10 °C – a combined absorption-ejector chiller (with using a refrigerant low-temperature air cooler as the second stage of air cooling). The effect of air-cooling was assessed by comparing the increase in the production of mechanical energy as a result of an increase in the power of a gas turbine unit and fuel saved during the month of July for 2015-2018 in accumulating. Deeper air cooling at the inlet of the gas turbine unit to a temperature of 10 °C in a combined absorption-ejector chiller compared to its traditional cooling to 15 °C in an absorption bromine-lithium chiller provides a greater increase in net power and fuel saved. It is shown that due to a slight discrepancy between the results obtained for 2015-2018, a preliminary assessment of the efficiency of air cooling at the inlet of gas turbine plants can be carried out for one year.

РЕЗЕРВИ ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ ТРАНСФОРМАЦІЇ ТЕПЛОТИ УСТАНОВКИ АВТОНОМНОГО ЕНЕРГОЗАБЕЗПЕЧЕННЯ

It is analyzed the efficiency of heat conversion in the integrated electricity, heat and cooling supply of the enterprise. The installation for energy supply includes two JMS 420 GS-N.LC GE Jenbacher cogeneration gas engines manufactured as cogeneration modules with heat exchangers for removing the heat of exhaust gases, scavenge gas-air mixture, cooling water of engine and lubricating oil. The heat of hot water is transformed by the absorption lithium-bromide chiller AR-D500L2 Century into the cold, which is spent on technological needs and for the operation of the central air conditioner for cooling the incoming air of the engine room, where from it is sucked by the turbocharger of the engine. The presence of significant heat losses, which account for about 30% of the total heat removed from the cogeneration gas piston module and is due to the inconsistency of the joint operation modes of the absorption lithium-bromide chiller and the gas piston engine, was revealed. This inconsistency is caused by the contradictory conditions of their effective operation according to the temperature of the return coolant at the outlet of the absorption lithium-bromide chiller and the entrance to the engine cooling system. The thermal state of the gas piston engine is ensured by maintaining the temperature of the return coolant at the entrance to it is not higher than 70 °C. At the same time, during the transformation of the heat of the coolant into the cold in an absorption lithium-bromide chiller, the temperature decreasing in the machine is no more than 10 ... 15 °С, that is, up to 75 ... 80 °С, if the temperature of the heat coolant outlet from the cogeneration gas piston module, i.e. at the inlet of the absorption lithium-bromide chiller, 90 °С. Therefore, the return coolant is additionally cooled in the "emergency heat release" radiator by removing its heat into surroundings. It is shown the possibility of increasing the cooling capacity of the system by conversion of the return coolant exhaust heat into cold in absorption lithium-bromide and ejector chillers through the data procession of monitoring the heat conversion system in the integrated energy plant.

АНАЛІЗ ЕФЕКТИВНОСТІ ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ КОГЕНЕРАЦІЙНОГО ГАЗОПОРШНЕВОГО МОДУЛЯ НА ЧАСТКОВИХ НАВАНТАЖЕННЯХ

The fuel efficiency of the reciprocating gas engine deteriorates with the increase of ambient air temperatures at the inlet to the radiator of the recirculating cooling water system for cooling the scavenge gas/air mixture at the inlet of the working cylinders and the air at the inlet of the scavenge air turbocharger. The peculiarity of cogeneration reciprocating gas modules of plants for combined production of electricity, heat, and cold is the operation mainly at partial loads according to the schedules of consumption of electricity, heat, and cold. The efficiency of cooling air of cogeneration gas module on the partial loads was analyzed on the example of an integrated power supply installation, which includes two cogeneration reciprocating gas engines JMS 420 GS-N.LC GE Jenbacher, manufactured as the cogeneration modules with exchangers using the heat of exhaust gases, scavenge gas-air mixture, cooling water of the engine shirt and lubricating oil for heating water. Hot water heat is transformed by the AR-D500L2 Century absorption lithium-bromide chiller into a cold that is spent on technological needs and for the operation of a central air conditioner that cools the engine room income air from where it is sucked by a scavenge air turbocharger. Because of significant heat influx from working engines and other equipment, as well as through the enclosures of the engine room from the outside to the air-cooled in the central air conditioner in the engine room, from where it is sucked by a turbocharger, the air temperature at the inlet of the turbocharger is quite high: 25...30 °C. At elevated temperatures of the ambient air at the inlet of the radiator for cooling scavenge gas-air mixture and the air at the turbocharger inlet the fuel economy of engine is falling, which indicates the need for efficient cooling of air. The efficiency of cooling the air of the reciprocating gas module was estimated by a reduction in the consumption of gas fuel and an increase in electric power of the engine. For this purpose, the data of monitoring on the fuel efficiency of the reciprocating gas engine with the combined influence of the ambient air temperature at the inlet of the radiator and the air at the turbocharger inlet were processed to obtain data on their separate effects and to determine the ways to further improve the air cooling system of the reciprocating gas module.

АНАЛІЗ ЕФЕКТИВНОСТІ ОХОЛОДЖЕННЯ ПОВІТРЯ КОГЕНЕРАЦІЙНОГО ГАЗОПОРШНЕВОГО МОДУЛЯ УСТАНОВКИ АВТОНОМНОГО ЕНЕРГОЗАБЕЗПЕЧЕННЯ

The analysis of the efficiency of cooling air of cogeneration gas-piston module of installations for combined production of electric energy, heat, and cold is performed. The installation for energy supply includes two JMS 420 GS-N.LC GE Jenbacher cogeneration gas-piston engines manufactured as cogeneration modules with heat exchangers for removing the heat of exhaust gases, scavenge gas-air mixture, cooling water of engine and lubricating oil. The heat of hot water is transformed by the absorption lithium-bromide chiller AR-D500L2 Century into the cold, which is spent on technological needs and for the operation of the central air conditioner for cooling the incoming air of the engine room, wherefrom it is sucked by the turbocharger of the engine. The temperature of the scavenge gas-air mixture at the entrance to the working cylinders of the engine is maintained by the system of recirculating cooling with the removal of its heat into surroundings by the radiator. Because of significant heat influx from working engines and other equipment, as well as through the enclosures of the engine room from the outside to the air-cooled in the central air conditioner in the engine room, from where it is sucked by a turbocharger, the air temperature at the inlet of the turbocharger is quite high: 25...30 °C. At elevated temperatures of the ambient air at the inlet of the radiator for cooling scavenge gas-air mixture and the air at the turbocharger inlet the fuel economy of engine is falling, which indicates the need for efficient cooling of air. The efficiency of cooling the air of the gas-piston module was estimated by a reduction in the consumption of gaseous fuel and the increase in electric power of the engine. For this purpose, the data of monitoring on the fuel efficiency of the gas-piston engine with the combined influence of the ambient air temperature at the inlet of the radiator and the air at the turbocharger inlet were processed to obtain data on their separate effects and to determine the ways to further improve the air cooling system of the gas-piston module.

Simulating and experimental research on a low-concentrating PV/T triple-generation system

A low-concentrating photovoltaic/thermal triple-generation system for heating, cooling and electricity is proposed in this study. The main components of the system are the low-concentrating PV/T module, high-temperature water source heat pump, lithium bromide absorption chiller and capillary net radiant ceiling. The annual system performance and the optimal capacity configuration of each component are stimulated by Transient System Simulation Program software. In addition, the outdoor experiments are carried out on the roof of a building in Changping, Beijing. In winter, the hot water produced by the low-concentrating PV/T module enters the heat pump evaporator for further heating, then through the pipes and enters the capillary net for building heating. In summer, the hot water enters an absorption lithium bromide chiller. The chilled water from the chiller enters the capillary net and lowers the room temperature. The experiments are conducted under different radiation conditions. The main parameters of the system are recorded. The results show that, under the low concentration condition, the system produces hot water of 45 °C–90 °C; meanwhile, the efficiency of PV cells stabilized approximately 10%. The lithium bromide absorption chiller operates stably, with the COP above 0.5. The low-concentrating PV/T triple-generation system provides a new idea for the comprehensive utilization of solar energy and energy cascade utilization.

МОДЕЛЮВАННЯ ПРОЦЕСІВ ОХОЛОДЖЕННЯ ПОВІТРЯ БРОМИСТОЛІТІЄВОЮ ХОЛОДИЛЬНОЮ МАШИНОЮ З ВИКОРИСТАННЯМ РЕЗЕРВУ ХОЛОДОПРОДУКТИВНОСТІ У БУСТЕРНОМУ ПОВІТРООХОЛОДЖУВАЧІ

The heat-humidity processes of gas turbine unit intake air cooling to the temperature of above 15 °C with the use of a cold water at the temperature of about 10 °C as a coolant and the absorption lithium-bromide chiller utilizing the turbine exhaust gas waste heat as a thermotransformer has been analyzed for daily changing ambient air temperatures and changeable heat loads on the air coolers as consequence. The computer programs of the firms-producers of heat exchangers were used for gas turbine unit intake air cooling processes simulation. It is shown that at decreased heat loads on the air cooler a surplus cooling capacity of the absorption lithium-bromide chiller exceeding current heat loads is generated which can be used for covering an increased heat loads on the air cooler and to reduce the cooling capacity of the absorption lithium-bromide chiller applied. To solve this task the cooling capacity required for gas turbine unit intake air cooling are compared with the surplus cooling capacity of the absorption lithium-bromide chiller exceeding current heat loads summarized during some period.The system of two-stage gas turbine unit intake air cooling with a buster stage of precooling air to the temperature of about 15 °C and a base stage of further cooling air to the temperature of about 15 °C by absorption lithium-bromide chiller as the base stage has been proposed. The water for a buster stage of precooling air is cooled by using the surplus cooling capacity of the absorption lithium-bromide chiller during decreased heat loads on the two-stage gas turbine unit intake air cooler and is collected in the thermal accumulator for the use during increased heat loads on the air cooler. The results of gas turbine unit intake air cooling processes simulation proved the reduction of cooling capacity of the absorption lithium-bromide chiller applied by 30-40 % due to the use of a buster stage of precooling air at the expanse of the surplus cooling capacity of absorption lithium-bromide chiller saved in the thermal accumulator. So the main conclusion has been made about the efficient use of such a two-stage air cooling with a buster stage of precooling air by surplus cooling capacity from the thermal accumulator and a base stage for further cooling air to the temperature of about 15 °C by an absorption lithium-bromide chiller as a perspective approach in refrigeration.

ОЦІНКА ЕФЕКТИВНОСТІ ГЛИБОКОГО ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГАЗОТУРБІННИХ УСТАНОВОК В РІЗНИХ КЛІМАТИЧНИХ УМОВАХ

The efficiency of deep air cooling at the inlet of gas turbine units of a simple scheme has been investigated for changed climatic conditions of operation during the month. For air cooling, the application of waste heat recovery chiller has been proposed, which transform the heat of exhaust gases of gas turbine units into the cold. The efficiency of air cooling at the inlet of gas turbine units to different temperatures has been analyzed: to 15°C – an absorption lithium-bromide chiller, which is used as the first high-temperature pre-cooling stage of ambient air and down to 10°C – a combined absorption-ejector chiller, which acts as the second low-temperature stage. The air cooling efficiency is compared for different climatic conditions using the example of Yuzhnoukrainsk (Ukraine) and Shanghai (China). The climate peculiarity of Shanghai is the high relative humidity of the air, respectively, and its moisture contents at the same time its high temperatures. As indicators for assessing the effectiveness of air cooling at the inlet of gas turbine units down to 15°C in an absorption lithium-bromide chiller and deep air cooling to 10ºС, in a combined absorption-ejector chiller used an increase in useful power and a reduction in specific fuel consumption. It is shown that, through extremely different thermal and humidity parameters of ambient air, it is cooling at the inlet of gas turbine units for the climatic conditions of Ukraine provides the current increase in useful power by 10...15%, and for the climatic conditions of China – 18…22%. However, it should be noted that deeper air cooling at the inlet of the gas turbine unite to a temperature of 10°C in a combined absorption-ejector chiller compared to its traditional cooling to 15°C in an absorption lithium-bromide chiller provides an increase in useful power for a temperate climate of Ukraine (for example, Yuzhnoukrainsk) by 70...90%, whereas for tropical climatic conditions of China (Shanghai) – by 30...35%.

Hierarchical Multi-Objective Fuzzy Collaborative Optimization of Integrated Energy System under Off-Design Performance

In order to solve the frequently occurred nonlinear working characteristics problem of the devices in integrated energy system (IES), where this nonlinear problem causes the offset of operation characteristics and design points of those devices, in this paper, the hierarchical multi-objective fuzzy collaborative optimization model of IES under off-design performance is proposed. Firstly, the high-order nonlinear models of devices under off-design performance, including fuel cell (FC), gas turbine (GT), absorption lithium bromide chiller (ABS), etc., are presented considering renewable energy and diversified storage devices, which can more accurately describe the actual working condition of devices. Secondly, according to the needs of different engineering application modes, the lower level collaborative optimization model of energy hub (EH) with economic, eco-friendly, primary energy saving, and renewable energy accommodation rate as optimization objectives is proposed, which can well adapt to and reflect real world energy system. Thirdly, based on the relationship between master and slave dispatch centers, the upper level modeling and optimal scheduling model of IES consisting of coupling power system, natural gas system, and heat system is proposed. Then, a multi-objective fuzzy collaborative optimization model for EH and IES is developed, where continuous differentiable Sigmoid function is taken as the membership function. Finally, simulation results show that the proposed models and optimal dispatch method can effectively solve the frequently occurred non-linear working characteristics problem of the devices in IES. The optimal results are suitable for planning, calculation, operation, dispatch of IES, which can reasonably reflect the operation characteristics of IES.

Analyzing the efficiency of moderate and deep cooling of air at the inlet of gas turbine in various climatic conditions

The efficiency of deep cooling air at the inlet of gas turbine unite to the temperature of 10 °С by waste heat recovery combined absorption-ejector chiller was analyzed in climatic conditions at Kharkov site, Ukraine, and Beijing site, China, and compared with the moderate cooling to the temperature of 15°C in traditional absorption lithium-bromide chiller. The refrigerant ejector chiller is chosen as the most simple and reliable in operation chiller. It was used as the low-temperature stage for subcooling the air precooled in absorption lithium-bromide chiller to the temperature about 15 °C. Both waste heat recovery absorption lithium-bromide chiller and ejector chiller use the heat of gas turbine unite exhaust gas to produce a cooling capacity. Air cooling at the inlet of gas turbine unite was investigated for varying climatic conditions during the year. The current values of temperature depression with cooling ambient air to different temperatures of 10 °C and 15 °C and corresponding cooling capacities required were calculated. The comparison of the effect due to gas turbine unite inlet air cooling was performed by annual fuel saving and power production growth. With this the current values of turbine power output increase and specific fuel consumption decrease due to cooling inlet air from current varying ambient temperatures to the temperatures of 10 °C and 15 °C were calculated. It was shown that annual fuel saving and power production growth have increased by 1,8 times for Kharkov (Ukraine) site climatic conditions and by 1,6 times for Beijing (China) site due to deep cooling air to the temperature of 10 °C by absorption-ejector chiller as compared with cooling inlet air to the temperature of 15 °C by absorption lithium-bromide chiller.

A new approach to increasing the efficiency of the ship main engine air waste heat recovery cooling system

The efficiency of integrated cooling air at the intake of Turbocharger and Scavenge air at the inlet of working cylinders of the main diesel engine of dry-cargo ship by transforming the waste heat into a cold by an Refrigerant Ejector Chiller (ECh) as the most simple in design and reliable in operation and by complex in design but more efficient Absorption Lithium-Bromide Chiller (ACh) was analyzed. A ship power plant of cogeneration type using the relatively low-grade heat of water of a heat supply system with a temperature of about 90 °C, that significantly complicates the problem of its conversion into cold were considered. Because of the insufficiently high efficiency of transformation of the heat of hot water (low coefficient of performance) as compared with steam, the resulting cooling capacity may not be enough for cooling intake air of the turbocharger and scavenge air, that raises the problem of the rational distribution of heat loads between the Turbocharger Intake Air cooling circuit (subsystem) and Scavenge air cooling circuit and the need to use chillers of various types. This takes into account the rational parameters of cooling processes of the scavenge air in the cogeneration high-temperature stage of scavenge air cooler, in the intermediate stage of traditional cooling air with seawater, and in the low-temperature stage for deep cooling of the scavenge air by using a chiller. A new approach is proposed to improve the efficiency of integrated cooling Intake Air of the turbocharger and Scavenge Air at the inlet of the working cylinders of the ship main engine of a transport ship, which consists in comparing the required cooling capacity and the corresponding heat needs during the trade route with the available heat of exhaust gases and scavenge air of the cogeneration power plant, determining the deficit and excess cooling capacity of heat utilizing cooling machines of various types, that allows to identify and realize the reserves of improving the efficiency of cooling intake air of the turbocharger and the scavenge air of the main diesel engine through the joint use of chillers of various types.

ВИКОРИСТАННЯ РЕЗЕРВУ ХОЛОДОПРОДУКТИВНОСТІ АБСОРБЦІЙНОЇ ХОЛОДИЛЬНОЇ МАШИНИ ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ

The processes of air cooling at the gas turbine unit inlet by absorption lithium-bromide chiller have been analyzed. The computer programs of firms-producers of heat exchangers were used for the gas turbine unit inlet air cooling processes simulation. The absorption lithium-bromide chiller refrigeration capacity reserve (the design heat load excess over the current heat loads) generated at the reduced current heat loads on the air coolers at the gas turbine unit inlet in accordance with the lowered ambient air parameters has been considered. The absorption lithium-bromide chiller refrigeration capacity reserve is expedient to use at increased heat load on the air cooler. To solve this problem the refrigeration capacity required for cooling air at the gas turbine unit inlet has been compared with the excessive absorption lithium-bromide chiller refrigeration capacity exceeding current heat loads during July 2017.The scheme of gas turbine unit inlet air cooling system with using the absorption lithium-bromide chiller refrigeration capacity reserve has been proposed. The proposed air cooling system provides gas turbine unit inlet air precooling in the air cooler booster stage by using the absorption lithium-bromide chiller excessive refrigeration capacity. The absorption chiller excessive refrigeration capacity generated during decreased heat loads on the gas turbine unit inlet air cooler is accumulated in the thermal storage. The results of simulation show the expediency of the gas turbine unit inlet air cooling by using the absorption lithium-bromide chiller refrigeration capacity reserve, which is generated at reduced thermal loads, for the air precooling in the air cooler booster stage. This solution provides the absorption lithium-bromide chiller installed (designed) refrigeration capacity and cost reduction by almost 30%. The solution to increase the efficiency of gas turbine unit inlet air cooling through using the absorption chiller excessive refrigeration potential accumulated in the thermal storage has been proposed.