Запропоновано підхід до визначення складових теплового навантаження системи кондиціонування припливного повітря (СКПП) з урахуванням поточних кліматичних умов експлуатації, який базується на гіпотезі розкладання поточних змінних теплових навантажень на відносно стабільну складову як базову для вибору встановленої (проектної) холодопродуктивності холодильної машини, що працює на номінальних або близьких йому режимах, і нестабільне теплове навантаження, що припадає на попереднє охолодження зовнішнього повітря при змінних поточних зовнішніх температурах. Для обґрунтування підходу до вибору складових теплового навантаження СКПП виконаний аналіз поточних значень питомих теплових навантажень на холодильну машину СКПП при охолодженні зовнішнього повітря від його змінної поточної температури до температур 10, 15 і 20 ºС. Показано, що виходячи з різного темпу приросту річного виробітку холоду, обумовленого зміною теплового навантаження у відповідності з поточними кліматичними умовами протягом року, необхідно вибирати таке проектне теплове навантаження на холодильну машину СКПП охолодження повітря (її встановлену потужність охолодження), яке забезпечує досягнення максимального або близького йому річного виробітку холоду при відносно високих темпах його збільшення. При цьому значення теплового навантаження, що припадає на попереднє охолодження зовнішнього повітря, розраховують за залишковим принципом як різницю раціонального загального теплового навантаження і її базової відносно стабільної складової. Запропонований метод доцільно використовувати при розрахунку проектної базової холодопродуктивності холодильної машини СКПП, що працює на номінальному або близьких йому режимах, і бустерной складової теплового навантаження на попереднє охолодження зовнішнього повітря при змінних поточних зовнішніх температурах з використанням енергозберігаючих методів: акумуляції надлишкового (невикористаного) холоду при знижених поточних теплових навантаженнях на СКПП і його витрачання на попереднє охолодження зовнішнього повітря, річкупераціі охолоджуючого потенціалу повітря, яке відводиться для попереднього охолодження зовнішнього повітря.
The efficiency of the outdoor air conditioning systems application depends on how full the installed cooling capacity is applied, that is, with a more complete load and for as long as the possible yearly duration in actual climatic conditions. The production of cold is taken as a criteria of a quantitative evaluation of the efficiency of applying the cooling capacity of air conditioning systems – the amount of cold produced in accordance with its current demand for air conditioning, which in turn depends on the current consumption of cooling capacity and its duration and equals to their multiplication. It is obvious that the maximum value of the current amount of cold produced/consumed indicates an effective application of the installed cooling capacity. However, since the current demands of cooling capacity and their duration, that is, the amount of cold produced/consumed, depending on the changing current climatic conditions, they are characterized by significant fluctuations, which makes it difficult to choose the installed cooling capacity of the air conditioning system. Obviously, if we determine the amount of cold produced/consumed by its current values and summarized during the year, it is possible to significantly simplify the choice of the installed cooling capacity. At the same time, the current amount of cold produced/consumed causes a change in the rate of increment of the annual cold production with a change in the installed cooling capacity, and the maximum rate corresponds to the installed cooling capacity, which provides its efficient use. Proceeding from a different rate of increment of annual cold production with an increase in the installed cooling capacity of the air conditioning system due to a change in heat load in accordance with current climatic conditions during the year, the value of design heat load on the air conditioning system (installed cooling capacity) that provides maximum or close to it the rate of increment of the annual production of cold, and hence the maximum efficient use of installed cooling capacity is chosen
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.
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.
Since the supply air conditioning systems operation effect depends on the cooling duration and depth, it is quite justified to estimate it by the value of the specific annual cold production, which is the product of the necessary cooling capacity for cooling the air to the target temperature multiplied by duration of operation at a given cooling capacity and, thus, considers current climatic conditions. Obviously, the realization of the cooling potential (air conditioning) of the ambient air depends on the installed (design) cooling capacity of the air conditioning units, which, in turn, must considering fluctuations in thermal loads by the current variable thermal and humidity parameters of the ambient air. With an increase in the temperature of the ambient air, fuel consumption for the production of a unit capacity (mechanical/electrical energy) increases, and, accordingly, the more harmful substances are removed to the atmosphere with exhaust gases. To reduce the negative impact of unproductive fuel consumption during the operation of air conditioning systems at elevated ambient temperatures, resort to various methods for determining the installed cooling capacity of the installation, to reduce it. In the work, the ecological efficiency of air cooling is studied considering the climatic operating conditions for the Kyiv city that are variable during the year. The annual reduction in emissions of carbon dioxide CO2 and nitric oxide NOX was chosen as indicators for assessing the environmental effect of air cooling. It has been shown that when choosing the installed cooling capacity, by the method of ensuring the maximum growth rate of the annual cold production considering the increase in the installed cooling capacity of the chiller, there is a greater reduction in specific fuel consumption compared to the method of choosing the maximum annual cold production, respectively, and harmful emissions. When comparing the methods for choosing the design cooling capacity, air cooling to 15 °C provides a reduction in carbon dioxide CO2 emissions of more than 34 t for 2017 for the climatic conditions of Kiev, in favor of the method of ensuring the maximum growth rate of annual cold production, and nitric oxide NOX – about 5,8 t.
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