Comparison of Mixed H 2 H∞ with Regional Pole Placement Control and H 2 Optimal Control for the Design of Steam Condenser

This paper investigates the comparison between mixed H 2 /H∞ with regional pole placement control and H 2 optimal control for the design of steam condenser. The comparison have been made for a step change in the steam condenser pressure set point for a step change of 10 & 23 seconds using MATLAB/Simulink environment for the steam condenser with mixed H 2 /H∞ with regional pole placement controller, steam condenser with H 2 optimal controller and steam condenser without controller. The steam condenser with mixed H 2 /H∞ with regional pole placement controller presented excellent and superior dynamic performance in response to the two step changes and an improvement in settling time. The overall simulation results demonstrated that the steam condenser with mixed H 2 /H∞ with regional pole placement controller can be an efficient alternative to the steam condenser with H 2 optimal controller for the steam condenser

Optimasi Kecepatan Putar Fan Pada Air Cooled Condenser Berbasis Fuzyy-PID di Unit WHRPG SEMEN INDONESIA TUBAN

Waste Heat Recovery Power Generation (WHRPG) is a steam power generation system that utilizes exhaust gas heat from industrial production, in this way reducing CO2 gas emissions by 122,358 tons/year. In addition, the plant with WHRPG installation system is very cheap and environmentally friendly because without using coal fuel in general, but the exhaust gas to produce steam that will be used for electricity generation process on WHRPG. In this WHRPG plant, researchers want to know the operational reliability of the fan on the air cooled condenser to the performance of the condenser by adjusting the fan speed in accordance with changes in the temperature of the condenser exhaust turbine, so that the high temperature of the condenser is reduced and the condensation process is accelerated and how to run fuzzy-pid control to determine the rotational speed of the fan to changes in the temperature of the exhaust turbine in the condenser. To determine the optimal fan operation on the performance of air cooled condenser, the researchers used Fuzzy-PID based method. This study uses simulation with matlab 2018A software. In this study when the condenser pipe without a fan as a cooling medium the temperature produced is 80°C, this temperature increases from the initial 30°C, the increase in temperature is caused by heat flow from the turbine exhaust fluid with a calorific value of 272.22222244. To lower the temperature in the condenser required 5 fans as a cooling medium, in this process called forced convection heat transfer with voltage values respectively on the fan is 113.8 V, 125.5 V, 137.7 V, 150.4 V, and 163.8 V and fan speeds of 500Rpm, 525Rpm, 550Rpm, 575Rpm, and 600Rpm. With the performance of the fan condenser pipe temperature can drop to 33.30°C to lower the temperature at the expected sett point is 32°C then the performance of the condenser fan needs to be controlled using fuzzy-pid method. From this study it can be concluded that by controlling the condenser fan using fuzzy-pid method can reduce the temperature in the condenser pipe in accordance with the expected sett point temperature is 32°C

Heat recovery refrigeration in New Zealand dairy sheds : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Agricultural Engineering at Massey University

Increased energy costs initiated an investigation into refrigeration heat recovery as one conservation alternative available for reducing water heating costs on farm dairies. A theoretical energy balance was conducted, from which the potential of recovering refrigeration condenser heat was estimated at up to 60% of the water heating energy requirements. Preliminary tests with heat exchangers lead to the use of a tube-in-tube, counter flow, heat exchanger with fins on the refrigerant side, and cores on the water side, to improve the heat transfer characteristics. The exchanger, designed to provide 300 litres of 60°C water from a 2.25 kw refrigeration system cooling 2000 litres of milk per day, had an area of 0.84 m2, and an overall thermal conductance of 100 W.m-2.°C-1. This heat exchanger was inserted between the compressor and condenser of the refrigeration plant and tested with two condenser systems (air and water), four condenser pressures (6.5 bar, 7.5 bar, 10 bar and 12 bar), two milk inlet temperatures(23°C and l8°C), and two milk final temperatures (4°C and 7°C). In addition, tests on receiver pressure and suction superheat were performed to determine overall system performance. Increasing condenser pressure increased cooling times from 2 hours 32 minutes to 3 hours 17 minutes, after the completion of the 1200 litre morning milking (thus failing to comply with the 3 hour cooling regulation at high condenser pressures.) Also, C.O.P. decreased from 3.05 to 2.35 for the water cooled condenser system (2.70 to 2.00 for the air cooled condenser system due to fan power consumption). Gross heat recovery rose from 4.2 kWh.day-1 .m-3 to 8.l kWh.day-1 .m-3 for the water cooled system, giving water outlet temperatures of 45°C to 64°C as condenser pressure rose. The corresponding ranges for air cooled condensers were 3.8 kWh.day-1 .m-3, to 6.6 kWh .day-1 .m-3, and 38°C to 55°C. Changing milk inlet and final temperatures gave a proportional change in cooling times and total heat recovery, but had no effect on C.O.P. or heat recovery rates. Suction superheating increased total heat recovery by 15%, and water outlet temperatures by 9%. Increases in gross heat recovery with increasing condenser pressure were partially offset by additional compressor power, and yielded nett heat recoveries of 4.0 kWh.day-1 .m-3 to 6.0 kWh.day-1 .m-3 for water cooled, and 3.6 kWh. day-1 .m-3 to 4.3 kWh. day-1 .m-3 for air cooled, condenser systems. The maximum gross and nett heat recoveries (at 12 bar condenser pressure) were applied to the energy requirements of a monitored 220 cow town supply dairy. This analysis showed that the gross heat recovery was 51% of the water heating requirements, but the nett heat recovery dropped to 17% of the total heating and refrigeration demand. Based on current electricity and equipment prices, it is estimated that the payback period for this level of recovery would be 16-17 years. Changing the electricity pricing structure, to reflect up to a 1:3 differential in favour of water heating power costs, results in the 6.5 bar condenser pressure giving optimum results, but the nett returns are significantly lower than those reported. The potential for improved savings is greater from larger capacity systems as the capital investment is not proportionally increased with an increase in scale

Radiation-cooled Dew Water Condensers Studied by Computational Fluid Dynamic (CFD)

Harvesting condensed atmospheric vapour as dew water can be an alternative or complementary potable water resource in specific arid or insular areas. Such radiation-cooled condensing devices use already existing flat surfaces (roofs) or innovative structures with more complex shapes to enhance the dew yield. The Computational Fluid Dynamic - CFD - software PHOENICS has been programmed and applied to such radiation cooled condensers. For this purpose, the sky radiation is previously integrated and averaged for each structure. The radiative balance is then included in the CFD simulation tool to compare the efficiency of the different structures under various meteorological parameters, for complex or simple shapes and at various scales. It has been used to precise different structures before construction. (1) a 7.32 m^2 funnel shape was studied; a 30 degree tilted angle (60 degree cone half-angle) was computed to be the best compromise for funnel cooling. Compared to a 1 m^2 flat condenser, the cooling efficiency was expected to be improved by 40%. Seventeen months measurements in outdoor tests presented a 138 % increased dew yield as compared to the 1 m^2 flat condenser. (2) The simulation results for 5 various condenser shapes were also compared with experimental measurement on corresponding pilots systems: 0.16 m^2 flat planar condenser, 1 m^2 and 30 degree tilted planar condenser, 30 m^2 and 30 degree tilted planar condenser, 255 m^2 multi ridges, a preliminary construction of a large scale dew plant being implemented in the Kutch area (Gujarat, India)

Numerical study of a passive solar still with separate condenser

A passive solar still with separate condenser has been modeled and its performance evaluated. The system has one basin in the evaporation chamber and two basins (middle and upper) in the condenser chamber, with a glass cover over the evaporator basin and an opaque condensing cover over the upper basin. The evaporator, middle and upper basins yield the first, second and third effects respectively. The top part of the condensing cover is shielded from solar radiation to keep the cover relatively cool. Water vapor from the first effect condenses under the glass cover while the remainder of it flows into the condenser, by purging and diffusion, and condenses under the liner of the middle basin. The performance of the system is evaluated and compared with that of a conventional solar still under the same meteorological conditions. Results show that the distillate productivity of the present still is 62% higher than that of the conventional type. Purging is the most significant mode of vapor transfer from the evaporator into the condenser chamber. The first, second and third effects contribute 60, 22 and 18% of the total distillate yield respectively. It is also found that the productivity of the solar still with separate condenser is sensitive to the absorptance of the evaporator basin liner, mass of water in the evaporator and middle basins, and wind speed. The mass of water in the upper basin has a marginal effect on distillate production. Other results are presented and discussed in detail

Pumped two-phase heat transfer loop

A pumped loop two-phase heat transfer system, operating at a nearly constant temperature throughout, includes a plurality of independently operating grooved capillary heat exchanger plates supplied with working fluid through independent flow modulation valves connected to a liquid supply line, a vapor line for collecting vapor from the heat exchangers, a condenser between the vapor and the liquid lines, and a fluid circulating pump between the condenser and the heat exchangers

Preliminary results from the testing of an advanced passive solar still incorporating a shielded condenser

An advanced passive solar still with separate condenser has been studied theoretically and experimentally. The system has one basin in the evaporation chamber and two basins (middle and upper) in the condenser chamber, with a glass cover over the evaporator basin and an opaque condensing cover over the upper basin. The evaporator, middle and upper basins form the primary, secondary and tertiary effects respectively. The top part of the condensing cover is shielded from solar radiation and heat. Water vapor from the primary effect condenses under the glass cover while the remainder of it flows into the condenser, by purging and diffusion, and condenses under the liner of the middle basin. Outdoor tests of the present solar still and a conventional system were conducted at the University of Strathclyde. The two systems are also simulated under the same meteorological conditions. It is found that the solar shield effectively keeps the condenser cover relatively cool. Under favorable weather conditions the present solar still produced up to 34% more distillate than the conventional type. Experimental and estimated results are in close conformity. It appears that the new solar still can be exploited within and outside the tropical region

Modeling and Simulation of Condensation on Plastic Condenser Cooling under Night Sky

The Kutch region of north-west India is hot and semiarid, chronically short of drinking water. Dew forms frequently in the areas near the coast, over a span of eight-month (October- May) coinciding with the entire dry part of the year. Dew water is potable and safe. Dew harvest systems - devices to condense and collect dew - have been developed which could be installed on building roofs (condenser-on-roof), open ground (condenser-on-ground) and on frames (condenser-on-frames). The key component is the condenser, made of thin plastic film insulated underneath, which cools at night by radiative exchange with cloud-free sky. Condensation occurs when the film cools to or below the dew point of the surrounding air and humidity level is high - upwards of 85%. Over the season of eight months, 15 – 20 mm of dew water can be harvested. In this region where rainfall is very erratic and in normal years only 300 mm, harvested dew water can be an appreciable supplement. It can also be a small but critical supply for plants in nurseries. Design principle of efficient dew condenser is discussed and dew water collection in some recently installed working systems reported.