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NET Runtime 6. These releases are supported for production use since they have a go-live license. Release notes Latest release date Full version 6. These releases are generally not supported for production use. Hoogbegaafde leerlingen en wiskunde in de basisvorming. Meer- en hoogbegaafde en hoog intelligente leerlingen. Concept mapping voor hoogbegaafde en niet-hoogbegaafde leerlingen Effecten van begeleiding.
Programma Conferentie voor hoogbegaafde leerlingen Vrijdag 23 januari Beleid hoogbegaafde en begaafde leerlingen KBS de Rietkraag. Programma Conferentie voor hoogbegaafde leerlingen Vrijdag 6 november Protocol hoogbegaafdheid.
Een doorgaande lijn voor hoogbegaafde leerlingen. Beleid inzake meer- en hoogbegaafde leerlingen Agatha Snellenschool juni Their initial and running costs are low and cooling capacity is also low. For more humid locations, mechanical chillers are the alternative solution. Absorption chillers are used when the plant is in a combined cycle or cogeneration mode and has access to low-pressure steam.
Multiple-Choice Questions c hydro power plants d nuclear power plants Handbook of Energy Audit Q-3 Which one of the following is not an advantage of performing energy audit of a power plant? Mechanical drive To drive steam-powered turbines as an option of electricity purchased from a grid. Drying To dry agricultural and chemical products. Injecting For agitation or blending in chemical and petroleum process. Quenching To regulate the reaction temperature in an exothermic reaction process by direct injecting in the process.
Contd Energy Audit of Steam-Distribution Systems Process Application of steam Diluting To dilute process gas and thereby reduce coke formation on the surface of a heat exchanger. Pressure regulating To control partial pressure of a reaction process, steam is injected with reactants.
Transporting To transport the products, steam is injected in the process for entrainment. Stripping To remove contaminants from a process fluid. Fractionating To separate components having different boiling points in a distillation tower. Ejecting To maintain vacuum in the process. The water and sewage costs, and treatment cost is 0. Under normal conditions, the bucket hangs down, pulling the valve off its seat. Condensate flows under the bottom of the bucket filling the body and flowing away through the outlet.
When steam accumulates below the bucket, it raises it and lifts the lever and thereby shuts the outlet. It remains off till the steam condenses or vents off. It has good tolerance to water-hammer condition. It can be used in superheated steam lines. Small hole size discharges air very slowly. Not suitable for fluctuating pressure applications. Energy Audit of Steam-Distribution Systems Type of steam trap Float-type mechanical steam trap Working-principle subcategory Cut-section image The ball float-type trap operates by sensing the difference in density between steam and condensate.
The condensate accumulating in the valve chamber lifts the valve off from its position and releases condensate. New versions have thermostatic air vents for automatic release of air. Thermodynamic In this robust and simple steam trap trap, dynamic effect of flash steam is utilized.
During start-up, the steam pressure raises the disc and cool condensate and air is discharged. When flash-steam pressure builds up above the disc, it is forced down and sealed.
Condensation of steam reopens the valve. Balanced The operating element is a pressure steam capsule containing a special trap liquid and water mixture whose boiling point is below water. The capsule is in relaxed condition at cold temperature. As the condensate passes through it, the liquid in the capsule expands and valve shuts. Heat loss from the trap cools the water surrounding the capsule and restores original position. Linear behaviours for all types of condensate load and not affected by fluctuations in mass-flow rate and pressure; it is water-hammer resistant.
A valve operates best in its range of pressure difference for higher pressure difference; it will close and will not pass condensate. Long service life, compact, Peripheral outlets simple; and large capacity. It can work in waterhammer and vibration, easy to maintain.
It will not work in low differential pressure. Open Valve open Closed Vaporised fill Small, lightweight, and has a large capacity. Valve is full open during start-up condition allowing maximum condensate removal. Simple to maintain. It may damage by waterhammer or corrosion at long run.
It will not open until the condensate temperature drops below steam temperature. Contd Handbook of Energy Audit Type of steam trap Working-principle subcategory Cut-section image Features Open Bimetallic steam It is made of two dissimilar trap metal strips welded together. The element deflects when heated. Compact, open while start-up, can withstand water-hammer and corrosive condensate and high steam pressure.
It does not respond quickly to change in load or pressure because the element is slow to react. Closed A single bimetal strip may not meet required power; hence, a large mass is required. Impulse steam trap It consists of a hollow piston A with a piston disc B and both are placed in a tapered piston C. The valve is lifted up in case of accumulation of steam. Labyrinth steam It consists of a series trap of baffles which can be adjusted by a handwheel. Hot condensate passing between the baffle and trap casing expands and drops in pressure.
It is good at venting air. Tight shut-off is not possible as some steam continuously leaks Condensate out through the vent. Extremely small clearance is easily affected by dirt. Condensate in Condensate out Small and compact and have less chances of mechanical failure. Manual adjustment is required. P bar. Multiple-Choice Questions 1. They are often called comfort air-conditioning systems.
In manufacturing buildings, air-conditioning systems are provided for product processing or for the health and comfort of workers as well as processing and are called processing air-conditioning systems. Cold storages are used for food preservation. Most refrigeration systems used for air-conditioning are vapour-compression-cycle-based systems.
Vapour absorption is still more popular where waste heat is available and high initial cost is allowable. Air-expansion refrigeration systems are used mainly in aircraft and cryogenics lowtemperature refrigeration. Basic processes of air-conditioning systems are mentioned here: 1. Sensible cooling 2. Sensible heating 3. Humidifying 4.
Dehumidifying 5. Air cleaning 6. Air change 7. Air movement In sensible cooling and heating processes, heat is removed or added in conditioned space to maintain the temperature. Air cleaning is removing dust and other particulates, biological contaminants to maintain air quality. Air change is the process of exchanging air between the outdoor and indoor to maintain oxygen level, air quality, and freshness. Air movement is to control air circulation.
Out of the basic seven processes, the climate decides the required processes which may again vary throughout the year depending on whether the climate is hot and humid or cool and dry. The arrangement is provided which closes off the outside air intake when the system is switched off as well as when the power is off. It is also Mixing Chamber air in this chamber.
Air returning from the room mixes with the outside fresh air ventilation Return air from the space Outside air Fan Humidifier Cooling coil Filter Figure 9. Filter so that it cleans the return air and the ventilation air. It also prevents heating and cooling coil across it. Heating and Cooling Coils The heating coil increases air temperature and the cooling coil thermostats. It adds moisture and is controlled by a humidistat.
Fan It supplies air to the space though a duct. Based on their size, construction, and Energy Audit of HVAC Systems Air conditioning Individual system Space air conditioning Evaporative cooling air conditioning Desiccant based air conditioning Thermal storage air conditioning Clean room air conditioning Central air conditioning Chart 9. Window air conditioners are installed in a window or through a wall, while in a split or package air conditioner, indoor and outdoor units are mounted separately.
An outdoor condensing unit consists of a compressor and condenser, and an indoor air handler is located at a more advantageous location with reduced noise level. Individual systems are factory-assembled units. Individual systems have main components like, evaporator, compressor, condenser, capillary evaporator, the refrigerant evaporates and absorbs room heat directly; hence, it is known as direct expansion DX coil.
The system schematic is shown in Figure 9. Supply outlet Room air conditioner Return grille Figure 9. It usually has a short-supply and no-return ducts. Space air-conditioning systems are usually employed with a separate outdoor ventilation air system to provide outdoor air for the occupants in the conditioned space.
Evaporative-cooling air-conditioning systems use the cooling effect of the evaporation of liquid water to cool an airstream directly or indirectly. When an evaporative cooler provides only a portion of the cooling effect, it becomes a component of a central hydronic or a packaged unit system. An evaporative cooling system consumes low energy as compared to vapour-compressionbased air-conditioning systems due to absence of a compressor, but it can perform well only in dry atmosphere.
A desiccant-based air-conditioning system is usually a hybrid system of There are two airstreams in a desiccant-based air-conditioning system: a process airstream and a regenerative airstream. Process air can be all outdoor air or a mixture of outdoor and recirculating air. Process air is also conditioned air supplied directly to the conditioned space or enclosed manufacturing process, or to the Air-Handling Unit AHU , Packaged Unit PU , or terminal for further treatment.
Regenerative airstream is a high-temperature airstream used to reactivate the desiccant. A desiccant-based air-conditioned system consists of the following components: rotary desiccant and piping.
In a thermal storage air-conditioning system, the electricity-driven refrigeration compressors are operated during off-peak hours. Stored chilled water or stored ice in tanks is used to provide cooling in buildings during peak hours when high electric demand charges and electric energy rates are in effect. A thermal storage airconditioning system is always of central air-conditioning type.
Further details of thermal storage type of air-conditioning systems are given in Section 9. Clean-room or clean-space air-conditioning systems serve spaces where there is a need for critical control of particulates, temperature, relative humidity, ventilation, noise, vibration, and space pressurization.
In a clean-space air-conditioning system, the quality of indoor environmental control directly affects the quality of the products produced in the clean space. Energy Audit of HVAC Systems A clean-space air-conditioning system consists of a recirculating air unit and a make-up air piping work, pumps, refrigeration systems, and related controls.
A central hydronic air-conditioning system or central air-conditioning system uses a central zones of conditioned space. The heat capacity of water is times higher than that of air; hence, or cool the conditioned space. However, the system becomes more complicated and expensive for small size. Cooling tower Ppump. A person generates heat by digestion of food metabolism and loses heat by conduction, convection, radiation, and evaporative cooling by perspiration which is the primary heat-loss mechanism.
There are many parameters which affect the amount of heat released by our bodies, namely, activity of a person, surrounding atmospheric temperature and humidity, air motion, clothing, metabolic rate, etc. Figure 9. Dry air is made of nitrogen, oxygen, and minute portions of other gases. The amount of water vapour varies greatly for different locations and weather conditions. Psyhrometric terms are explained here. Dry-bulb temperature is measured by a standard thermometer with a dry-sensing bulb.
Wet-bulb temperature is measured by a thermometer using a sensing bulb covered with a wet wick and the thermometer is rotated in air. Moving of the thermometer in air makes the water evaporate from the wick, absorbing latent heat of evaporation from the wick, which lowers bulb temperature. The amount of evaporation is decided by the relative humidity of air.
An instrument measuring dry-bulb and wet-bulb temperatures is known as a sling psychrometer Figure 3. Relative humidity is the ratio of the amount of water vapour present in the sample air and the amount of water vapour in saturated air. In an ideal vapour-compression refrigeration cycle, the refrigerant enters the compressor as a saturated vapour and is compressed isentropically.
Compressed vapour is cooled in a condenser to the saturated liquid state and then expands from high pressure to low pressure in the expansion device. A mixture of the refrigerant liquid and vapour comes out of the expansion of evaporation, which is known as cooling effect.
Schematic arrangement of vapour-compression refrigeration cycle and thermodynamic representation on ph and Ts diagrams are shown in Figures 9. Condenser 3 2 Compressor Expansion valve Evaporator 4 Figure 9. Table 9. The refrigerant coming out of the condenser is usually subcooled to a temperature lower than the saturated temperature corresponding to the condensing pressure of the refrigerant, shown in Figure 9.
This increases the refrigerating effect. The degree of subcooling depends mainly on the temperature of the coolant e. Thus, subcooing and superheating are advisable for better performance of vapour-compression refrigeration system. A typical ph chart for Ra refrigerant is shown in Figure 9.
Likewise, increase in condenser pressure decreases refrigeration capacity and power consumption increases. Thus, both these operating conditions are not advisable.
For multiple temperature applications like cold storages, dairy industry, etc. Basics of compressors available in capacity of 0. For small systems, hermetically sealed reciprocating compressors are used in which the compressor and motor are directly coupled and housed in a single unit.
Open compressors are more suitable for large systems. Low initial cost is the advantage of a reciprocating compressor; at the same time, it requires frequent maintenance. Centrifugal compressors are variable-volume displacement units of open as well as hermetic types.
They are available from to ton capacity. The main advantage of centrifugal Screw compressors are positive-displacement-type machines and are of single-screw, twinscrew, oil-type or oil-free type. Their capacity range is 20 to tons and they operate at high Handbook of Energy Audit compression ratio.
Main advantages of screw compressors are they are compact, lightweight, silent, Condenser Compressed high-pressure and high-temperature refrigerant vapour comes to the condenser, where it is condensed to liquid state by removing its latent heat and subcooled by removing sensible heat.
Air or water is used to remove heat of the refrigerant. Both have their inherent advantages and allocations. Air-cooled condenser does not require water, simple and less maintenance is involved but works at higher condensation temperature and air having less heat-carrying capacity requires more heat-transfer surface area.
Proper air circulation and regular cleaning are essential in air-cooled condensers. Mostly, a shell-and-tube arrangement is used for a water-cooled condenser. Expansion Valve the function of an expansion valve is to meter the liquid refrigerant in the evaporator and maintain a pressure difference between the condenser and evaporator.
Different expansion valves used in the HVAC industry are hand valve, capillary tube, etc. Water outlet Safety valve connection Water inlet Front cover Figure 9. It is made of a small-diameter tube and is suitable for company-assembled devices like refrigerator, water cooler, display type cabinets, window air conditioners, etc. It cannot regulate the amount of refrigerant so The most common expansion device is the thermostatic expansion valve which can control the more internal port, it is able to balance pressure more accurately and is known as a balanced expansion valve.
Evaporator Refrigerant evaporates and absorbs latent heat of evaporation from the surroundings in an evaporator. An air-cooled evaporator may be of natural circulation type or forced circulation type. Liquid-cooled heat exchangers are shell-and-tube type or plate-type. ShellRefrigerant The refrigerant plays the role of absorbing and transmitting heat in a vapourcompression refrigeration system.
Most common desirable properties of a refrigerant are pressuretemperature relationship it should not have excessively low pressure in the evaporator and high pressure in the condenser , freezing point, chemical stability, toxicity, ozone-depletion potential, global warming potential, and cost.
In addition to the listed components, controls, thermostats, high-pressure—low-pressure switches, relief valves, oil separators, solenoid valves, accumulators, dehydrators, insulations, etc.
The lower atmosphere is called the homosphere, and the upper atmosphere is called the stratosphere. In the mids, CFCs were widely used as refrigerants in mechanical refrigeration systems, to produce thermal insulation foam and to produce aerosol propellants for many household consumer products.
They are very stable. Halons are also halogenated hydrocarbons. If CFCs and halons leak or are discharged from a refrigeration system during operation or repair to the lower atmosphere, they will migrate to the upper stratosphere and decompose under the action of ultraviolet rays throughout decades or centuries. The free chlorine atoms react with oxygen atoms of the ozone layer in the upper stratosphere and cause a depletion of this layer. The theory of the depletion of the ozone layer was may cause skin cancer, a serious threat to human beings.
A cloudless homosphere is mainly transparent to short-wave solar radiation but is quite opaque to long-wave infrared rays emitted from the surface of the earth. Carbon dioxide CO2 has the greatest blocking effect of all; water vapour and synthetic CFCs also play important roles in blocking the direct escape of infrared energy. The phenomenon of transparency to incoming solar radiation and blanketing of outgoing infrared rays is called the greenhouse effect. This is known as the global warming effect.
Either mixing cooled air with heated or bypassed air or directly reheating cooled air is used to control the partial load conditions. Different types of CAV systems used presently are described below: CAVs with terminal reheat systems which require the circulated air to be cooled to meet design thermal loads. If partial thermal load conditions occur, reheat of pre-cooled air is required. CAV systems with terminal reheat in interior spaces and perimeter induction or fan-coil units For these systems, the energy waste is reduced at the perimeter spaces, since a large portion of the air supplied to the perimeter spaces is re-circulated within each space by either induction or fan-coil units.
All-air induction systems with perimeter reheat The induction units accept varying amounts of warm return air to mix with primary air for temperature control. The energy waste due to reheat is small for these systems.
However, extensive static pressure control is required at the terminals. Mixing cold air with hot air proportionally to meet the thermal load of the space controls the supply-air temperature. Energy waste occurs during partial thermal load conditions when mixing is needed. Variable Air Volume VAV systems provide a variable amount of supply air, conditioned at a constant temperature to meet the thermal loads in each space based on thermostat setting.
The air volume is controlled using outlet dampers, inlet vanes, and variable speed drives. Only cooled air is supplied at the central AHU while reheat is provided in each space depending on the thermal types are: VAV systems with terminal reheat which reduce the amount of air supplied as the cooling load lowers until a preset minimum volume is reached. At this limit, reheat is provided to the supply air to meet the thermal load. Because of this volume reduction, reheat energy VAV systems with perimeter heating units providing only cooling since heating is performed by other systems, such as hot-water baseboard units.
The heating units are controlled by outside air temperature, since the perimeter heating load is a function of the transmission losses. VAV double-duct systems which have cold-air and hot-air ducts and operate in a similar way to VAV systems with terminal reheat.
As the cooling load decreases, only cold air is supplied until a preset minimum volume is reached. At this limit, the hot air is mixed with the cold airstream. However, energy saving can also be considered, even if the existing system is a VAV. The potential for energy saving in HVAC systems depends on several factors, including their design, the method of operation, and their maintenance.
The auditor should estimate the existing volume of fresh air and compare this estimation to the amount of ventilation air required by the appropriate standards and codes. Some energy-conservation measures related to ventilation are described here. However, in may actually reduce cooling and heating loads through the use of airside economizer cycles. The potential of energy savings attributed to economizers is also discussed here.
First, evaluate the existing level of ventilation air through a mechanical system. The tracer-gas or enthalpy-balance technique can be used to determine the amount of fresh air entering a room. Once the existing ventilation air is estimated, it has to be compared to the ventilation requirements Energy Audit of HVAC Systems by the applicable standards. A damper controller receives signals from the CO2 sensor and The calculation of the energy saving by reducing ventilation air is given in Equation 9.
Use controls to shut off ventilation air during no-occupancy periods. On the other days, the HVAC system can operate at a reduced capacity. This is where a variable air-volume system with variable speed drives also called variable-frequency drives, or used.
If a building uses a constant-volume air-handling system with no variable-speed drives, the the appropriate rooms does not control the speed of the motor and does not save energy as well. Following components if driven through variable-speed machines will able to save energy.
Centrifugal air-handler fans 2. Centrifugal exhaust fans 3. Centrifugal chilled-water pumps 4. Centrifugal hot-water pumps 5. Cooling-tower pumps 6. Cooling-tower fans The following example shows the amount of energy saved with a variable-speed drive.
The lifespan of an HVAC equipment is 15 to 25 years and, hence, adopting a variable-frequency drive will give substantial return. Online payback calculators are available from various variable-frequency-drive manufacturers. It also reduces the long-term wear and tear on equipment.
The drives provide a soft start instead of slamming motors at full speed, so HVAC systems last longer, requiring less maintenance and causing fewer instances of unscheduled downtime. Multiple compressor chillers can be reciprocating, screw, or centrifugal, with capacities in part-load conditions. Variable-speed compressor chillers are, in general, centrifugal and operate with variable head pressure using variable-speed motors; therefore, they work best when their cooling load is most of the time below the peak.
Their typical capacity is in the range of to kW. The following example shows payback calculation of chiller replacement. Assume that the number of equivalent full-load hours for the chiller is per year, both before and after the replacement. Set the chiller water at the highest possible temperature to increase COP of the system.
Decrease condenser-water temperature for water-cooled condenser to improve the performance. Increase surface areas of the evaporator and condenser for more effective heat transfer. Enlarge refrigerant lines for lower friction. Carry out ozonation of the condenser water to prevent scaling and biological contamination. Use water-side economizers. In favourable weather conditions, water can be cooled by using cooling towers instead of chillers, this cooled water will be circulated through chiller circuits or heat-exchanger coils.
Evaporative cooling can be used in dry weather condition in series with chillers. It is discussed in Section 9. Use desiccant cooling for industrial applications. Subcooling the refrigerant before it enters the expansion device increases refrigeration capacity of the plant for the same amount of power consumption. Subcooling is achieved either by a suction-line heat exchanger or an external heat sink such as a small cooling tower or a ground-source water loop.
Duct leakage increases during summer. To reduce duct leakage, ensure that duct connections are securely fastened and use mastic sealants and gaskets. Incorporation of heatrecovery wheels into the air-conditioning system means more outdoor air at lower energy cost and reduced chiller load. In a typical installation, the wheel is positioned in an airhandling unit so that it is divided into two semicircular sections. Exhaust air passes out through one half and outdoor air enters time, the wheel is rotated.
Sensible heat is transferred as the Figure 9. Moisture and dry air e. Advantages of Heat-Recovery Wheel 1. Helps precondition the incoming fresh air 2. Easy to install in existing ventilation systems 3. Helps meet ventilation standards without adding operation cost 4. Maintains humidity level at no additional cost 5.
Some general areas where cooling loads are reduced are discussed here: 1. Size the air-conditioning system accurately. Estimate the load based on theoretical calculations to reduce the chances of oversizing the units. Consider differant factors like seasonal effects, working cycle, climatic changes, use of ground-source heat pump while designing the same.
Instead of using central or package air-conditioning systems, use evaporative coolers for Handbook of Energy Audit 4. In centrally air-conditioned room areas, certain applications like ovens, kitchens, cleaning rooms adds on the cooling load.
Isolate these areas to reduce the load on the system. Cold storages which are mainatined in minus range of temperatures have serious effect on performance due to ice build-up, frost, or frequent openings. Wind curtains and high-speed doors are popularly used solutions.
Similarly, to reduce condenser temperature, install a condenser of larger size and use water or evaporative cooled condenser. Light-colored roof coatings reflect solar radiation and reduce conducting potential Smaller cooling plant accurately sized to meet the reduced cooling load Insulating the roof helps decrease heat conduction to the inside of the building Roof-wetting lowers roof temperature by evaporative and radiative cooling Structural overhangs light shelves reduce solar gain Automatic louvers fixed louvers and solar screens block solar radiation Spectrally selective glazings let light in but keep heat out South Movable awnings provide shade Tree block solar radiation and provide cooling benefit throught avapotran spiration Figure 9.
To to the building. Reducing the friction of distribution system and pressure drop across the system improves the performance. As air has to travel a long path in an air-conditioning system and is occur, selecting components which offer minimum pressure drop will reduce running cost of the will consume less energy.
Friction in the fan ultimately turns into heat which is dissipated by the this system are listed below: reduced. Relatively warmer air is supplied to the room using this system, which improves the 3.
Air is supplied to the room from bottom and it moves towards ceiling; hence, heat load of light is carried away by leaving air which reduces effective cooling load and required cooling capacity of the HVAC system. The additional cost system is highly advantageous to buildings where frequenct internal changes are made.
In addition, this system offers easy excess for maintenance. In this system, the refrigerant is absorbed by a transport medium and compressed in a liquid form. Two commonly used absorption refrigeration systems are ammonia—water and lithium bromide— water. However, the absorption cycle uses different refrigerants and a different method of compression than the vapour-compression cycle.
The schematic of the vapour-absorption system is shown in Figure 9. The compressor of the vapourcompression refrigeration cycle is replaced with a generator and an absorber. The refrigerant vapour coming from the evaporator mixes with the returning absorbent and the mixture is pumped to the generator. Heating of the mixture in generator separates the refrigerant vapour at high pressure which is condensed in condenser, expanded in the expansion valve and evaporated in the evaporator similar to the vapour-compression refrigeration system.
In dry climates, use of evaporative cooling can be a costeffective option compared to a vapour-compression-based air-conditioning system. Alternatively, vapour compression and evaporative cooling can be used in combination to reduce operating cost of the system. As evaporative cooling has no compressor and works only with heat exchanger and th of a vapour-compressor-based system. Another advatange of evaporative cooling is it continuously supplies fresh air.
The cost of an evaporative cooler is not directly comparable because it depends on the type of end user, design, and material used and there are not many players in the market.
Evaporative cooling systems are of three types, namely, direct evaportive cooling, indirect evaporative cooling, and direct—indirect evaporative cooling. In direct evaporative cooling, water evaporates into the air and due to this, the temperature of air reduces.
The process is adiabatic saturation and is represneted in Figure 9. Temperature C Figure 9. A heat-exchanger surface will be wetted with water over which outside air will pass and due to evaporation of the water, the surface temperature of the heat exchanger will reduce and ultimately, the supply-air tempeature will reduce. The disadvantage of direct evaporative cooling is overcome in indirect cooling. The third type of evaporating cooling is direct—indirect type in which indirect cooling is used in shown in Figure 9.
The full line shows room-air path and the dotted line shows secondary-air air used to cool room air path. There are certain advantages of CFCs: they are CFC was widely used in domestic refrigerators and air conditioners domestic and mobile. Ozone-depletion potential 2.
Global-warming potential 3. Flammability 5. Thermal and chemical stability Suitable alternative refrigerants and their properties are listed in Table 9. The drawback of HFC is it is immiscible with naphthenic mineral oils and benzene oils; hence, alternative synthetic oils have been developed. These oils are hygroscopic and require more maintenance to ensure a moisturefree system.
Another change required with HFCa is resistant-grade electrical insulation for 9. For energy consumers and can contribute to a high extent. Reduction in energy and water consumption 2. Improved productivity due to maintained human comfort 3. Rainwater harvesting Handbook of Energy Audit Some design aspects of green buildings are listed here: 1.
Provision of charging points for electrically operated vehicles. Promote employees to use mass transportation and shared vehicles. More open space. Building orientation to maximize south and north exposure and minimize west and east exposure to follow the solar path. Placing windows and glazing on north wall to minimize heat gain and maximize day lighting. Use of low U-value glazing. Minimize building footprints to reduce impact on environment.
Maximize daylight usage. Use of rainwater harvesting and drip irrigation. Recycle grey water and reuse after treatment. Segregate and reuse building waste like paper and plastic. Promote use of on-site renewable energy and salvaged material for construction. Use of low-voltaic organic compound paints. Differant parameters controlled are HVAC, are tailor-made systems and require common network connections.
During summer, air conditioners of buildings are the largest contributor to peak electrical demand. The electricity consumption is peak during afternoon and evening hours and low at night and early-morning hours.
To meet this peak demand, utilities increase their generation capacity and during lean-demand periods, the power plants are operated at less capacity which affects the performance and return on investments. TES may be considered a useful tool to reduce the number of refrigeration machines by means of spreading the daytime load over a hour period.
This stored coolness is used during peak usually afternoon hours. Media used for thermal storage are of different types like chilled water, ice, eutectic salts, etc. Among them, the chilled-water system works on storage of sensible type of heat, while ice and eutectic salts work on storage of latent heat. Figures 9. Load shifting: Due to shifting of load during off-peak hours, advantage of daytime tariff Storage system chillers operate at full load during off-peak hours instead of conventional operation.
Less capacity and space required compared to conventional system. During night hours, outdoor temperature is less; hence, condensation occurs at low temperature and the net effect is rise in EER.
Easy to take up maintenance during off-peak hours. They operate with direct expansion unit and multiple indoor units with the difference that the multi-split unit turns ON or OFF in Pulse Modulating Valve PMV which is controlled by a microprocessor receiving signals from sensors located with each indoor unit. It ultimately controls the compressor speed to match cooling or heating load on the system.
Maximum system capacity is 70 kW approx. A schematic of a VRF system is shown in Figure 9. Precise humidity control. It is possible to achieve simultaneous cooling and heating. As shown in Figure 9. It provides superior excellent.
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