Mechanical Ventilation Options Of Dehumidification Engineering Essay

Mechanical airing is the usage of distributed and ducted air to and from centrally located fans in combination with heat recovery or humidification, chilling, heating or filtration. These types of systems are largely common used in infirmaries and private or commercial edifices where the lone manner to carry through liveable indoor air quality is by mechanical airing systems.

In metropoliss with big sums of flat and office edifices with a batch of Windowss where the difference between indoor and outside temperature is truly high, mechanical airing will be necessary. During hot seasons ( Panama twelvemonth unit of ammunition ) these edifices, and particularly edifices with " modern Architecture '' in which most of the facade country tends to be wholly glazed, experiment overheating. To accomplish equal indoor temperatures it is necessary to pull out the warm air from the inside before supplying cooled air to the inside. This type of system sometimes besides filters pollutants in the air. As these systems modify the entrance air supply, they are generically called A/C units.

Waste heat recovery from edifices can besides be accomplished by A/C. When waste heat is recovered, the consumption air will be conducted through a portion of the heat money changer that was antecedently being directed to the ambiance. The cured heat can be used to heat the air when needed or for other intents such as hot H2O proviso.

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The A/C systems and mechanical airing have an attached cost of energy which is necessary to run the fans, and this sum increases as the measure of filters additions in the edifice and makes it more hard to present the air in the inside. Recycling heat from these machines can cut down energy measures, but the bulk of the clip the usage of A/C and mechanical airing comes with an elevated cost at the beginning, every bit good as throughout care and running. In order to non hold bacterial jobs in the procedure, changeless care should be applied (Tomczyk 1995, p14 ) .

Stanley Mumma, Ph.D. , P.E. , 2001 performed research on the different combinations of the design of out-of-door air, which will now be briefly explained ( Mumma 2001, p28-30 ) .

In tropical climes where the sum of wet in the air is the most of import factor to take into consideration when planing the system to chill the edifice, dehumidification can be possible by using either chilling spirals or active drying agents ( liquid or solid ) . Regularly active drying agents are a good option when the DPT is less than 4A°C, and chilling spirals are a better option when the DPT is more than 4A°C. With a good choice and supported deep chilled H2O, competent for accomplishing a DPT of 7A°C seems to be the best option. The spiral competency can be inflected to equilibrate the transeunt burden conditions. Besides, off-peak A/C, which works with H2O thermic sedimentation or ice, can be used.

In Configuration 2 ( see figure 10 ) , for the stipulation of the outside air in front of the chilling spiral an heat content wheel which dehumidifies and cools the outside air is used, diminishing the burden on the chilling spiral. In climes where heating for winter is needed, the heat content wheel can be applied to moisturize and heat the out-of-door air, acquiring rid of the demand for a humidifier. To avoid frost creative activity on the wheel preheating is needed. The warming spiral and the runaround heat recovery coils carry through the same as in Configuration 1. Configuration 3 is about the same as Configuration 2, but with the runaround spirals superseded by a reasonable heat recovery wheel for warm up. In Configuration 2 the reasonable wheel wholly avoids the necessity for the warming spiral. The best combination for dedicated out-of-door air systems is supposed to uncouple the indoor reasonable and latent tonss.

The chief collectors of condensation in an A/C are the spirals. When there are major sums of humidness in the air, the spirals are traveling to absorb more H2O, which in the long tally means that the A/C is traveling to run for longer periods. The RH does n't hold any input in the thermoregulator of an A/C, but it has an input in the sum of power to chill the edifice, which affects the thermoregulator by puting it at a unvarying graduated table for longer timeframes.

To obtain an indoor degree of humidness around 60 % in hot-humid climes, auxiliary dehumidification must be provided. The bulk of machines in this type of clime addition the sum of humidness by 5 % to 10 % , which happens because the A/C does n't run at full power ( Christensen, Fang & A ; Winkler 2011, p4.7 ) .

Xia Fang, Winkler and Christensen in their reaserch for the National Renewable Laboratory 2011 tried out a properly sized 2-ton ( 7-kW ) A/C unit with reasonable heat ratio of 0.8 with different dehumidifier options:

1 ) thermoregulator reset,

2 ) A/C with energy recovery ventilator ( ERV ) ,

3 ) heat money changer ( hx ) -assisted A/C,

4 ) A/C with capacitor reheat,

5 ) A/C with desiccant wheel dehumidifier,

6 ) A/C with high-efficiency DX dehumidifier,

7 ) A/C with standard-efficiency DX dehumidifier.

In option ( 1 ) the sum of comparative humidness over 60 % caused the overcooling of the infinite by the A/C by 3A°C, which augmented its runtime and tend to overcool the inside, accordingly simplifying conveying the outside RH to the inside due to the high difference between outside and indoor temperatures. On the other manus, option ( 2 ) at part-load conditions was non able to command the humidness entirely.

In option ( 4 ) the system was unable to run into the interior humidness and established chilling temperature at the same clip. As in option ( 1 ) the overcooling of the infinite during dehumidification presented the same job and a big sum of A/C energy could be necessary.

In option ( 5 ) the desiccant wheel with heat rejected by the capacitor is regenerated with a drying agent dehumidifier ( see figure 11 ) , dividing the regenerative airstream from the supply airstream. The machine reduces de A/C run clip and provides dry and cool air to the indoors with a wet remotion rate of 120 pints/day ( 56.8 L/day ) .

Incorporated machines for humidness control in options ( 4 ) through ( 7 ) increase the sum of energy ingestion of the edifice. RH set points of 50 % make the sum of energy needed higher comparative to 60 % . Similarly, RH programmed at 50 % increases the tally clip for the A/C and the dehumidifier relation to RH programmed at 60 % , with the exclusion of option ( 5 ) for the A/C with desiccant wheel dehumidifier.

Within all the engineerings for active dehumidification, option ( 5 ) ( A/C with desiccant wheel dehumidifier ) is the lone that decreases the run clip of the A/C. The A/C burden is partly compensate pending dehumidifier operation due the desiccant wheel dehumidifier provide cool air.

Cooling burden and its importance in hot-humid conditionss.

The heat generated by people, visible radiations and equipment and the heat transferred across a room envelope ( floor, door, Windowss ) make up the entire edifice chilling burden ( see figure 12 ) . External burden is the transportation of heat that comes indoors trough the envelope, while the internal burden is all the remainder. The conditions, constructing type, and design vary the sum of external and internal tonss. Latent tonss ( which affect the wet content ) and reasonable tonss ( which affect the dry bulb temperature ) together make the entire chilling burden temperature.

Edifications should be classified as internally or externally loaded. In internally-loaded sophistications the heat addition from residents, contraptions, and visible radiations represents the chilling burden. In most of the instances edifices remain without alterations to the heat coevals from the internal heat beginnings, and, because the internal heat beginnings are greater compared to the heat transportation from the ever-changing milieus, the chilling burden of an internally-loaded sophistication remains about unvarying. In externally-loaded sophistications the heat transportation between the indoors and the precincts compose the chilling burden. In externally loaded edifices the chilling burden varies widely because the out-of-door temperature varies all the clip ( ASHRAE 2011, p87 ) .

The chilling burden extremum depends on the clip of twenty-four hours and out-of-door temperatures. Cooling burden alterations well throughout the twenty-four hours because of the Sun 's radiation, which makes it of import to take into consideration the unsure province procedure for ciphering the chilling burden. Not taking the internal beginnings into consideration for the chilling loads computation would non let accomplishment of the needed interior temperature. Therefore, it is really complicated to cipher the chilling burden exactly.

The heat that a organic structure absorbs and elevates its temperature without the organic structure experimenting a alteration in its physical province is called reasonable heat. Radiation, convection, and conductivity are the three ways that heat addition can be added to the learned infinite. The measure of reasonable heat addition at a given clip is non the same as the chilling burden at the same minute, due to the heat stored in the sophistication envelope. Merely heat by convection can turn into chilling burden right off. Reasonable heat burden is composed of: outdoor-air infiltration ; heat from residents, visible radiations, and contraptions ; solar additions trough glass ; airing air ; and heat coming in trough ceiling and walls.

Latent heat burden is the sum of wet added to the indoor infinite from internal vapour beginnings like residents or equipment, or from out-of-door air in footings of infiltration or airing to guarantee appropriate indoor air quality. Latent heat burden is made up of occupant motion and out-of-door wet from airing and infiltration. It is possible to boil a certain sum of liquid into indoor air of a room or intake a certain sum of H2O with a dehumidifier without altering the room air temperature. However, the vaporization of H2O into the indoor air infinite adds the latent heat of vaporization of the H2O to the entire heat in the air ( Dorsi & A ; Krieger 2004, p70 )

The room air does non instantly absorb the measure of heat emitted from people, solar radiation, equipment, etc. ( see figure 12 ) . Alternatively, indoor air ab initio absorbs merely a little sum. The bulk of heat from illuming and Sun is soaked up by surfaces in the inside, such as furniture and floors. Depending on the particular belongingss of the stuffs, the heat addition has a decrement component and a clip hold. As a consequence, this heat will be present or felt by the residents even good after the beginning of heat addition is gone.

Dedicated Outdoor Air Systems ( DOAS )

When it comes to amount and energy cost of air conditioning in hot-humid climes, one of the chief grounds of expensive monthly energy measures is that air conditioning is non designed to cover with the big sum of humidness in the air ( latent burden ) which is between 70 % and 100 % . With this sum of RH people feel a higher temperature and hence instantly take down the temperature of the thermoregulator, the bulk of times to between 16 and 18 grades Celsius.

The attack by and large being taken today is to divide the conditioning of out-of-door air and the handling of the entire latent burden from residuary reasonable chilling ( or warming ) . Such systems are by and large described as dedicated outdoor air being used to cut down the associated energy cost. The residuary reasonable burden on the infinite can be handled by a assortment of methods, by and large hydronic in nature - fan spiral units, beaming panels, chilled beams, for illustration.

DOAS or dedicated out-of-door system is a warming, airing and air conditioning system that on a regular basis uses two systems at the same clip: one to cover with the reasonable tonss and another one to manage the latent tonss.

Regular warming, airing and air conditioning systems, taking attention of more than one country, nowadays in some instances microbic jobs and limited thermic comfort. The chief intent of DOAS is to accomplish dedicated airing alternatively of airing as one portion of air conditioning. The out-of-door air system will take attention of the latent burden and one portion of the reasonable burden, and another system at the same clip will take attention of the reasonable burden depending on the climes and the machine employed besides DOAS do non use recirculated air, so micro bacterial job through the air wo n't happen ( Stanley Mumma and Shank 2011, p28-30 ) .

Research made by ASHRAE to happen out the best combination of air conditioning that can cover with the humidness in hot-humid climes in order to cut down the energy ingestion, shows that the dedicated air systems working together with reasonable chilling in the terminal units produces the best solution taking into consideration the followers:

• Employ energy recovery in learned out-of-door air to manage the indoor latent burden and some of the reasonable burden.
• For good air distribution airing, the airing should non be working together with the indoor conditioning machines.
• Achieve the treating of the reasonable tonss with a parallel system.
• Join together the energy conveyance and fire suppression.

Stanly A. Mumma, Ph.D. , Pe. made a research on the economic net income of different ceiling radiant chilling panels.

The three hydronic systems analyzed are: the radiant panel web, the dedicated outdoor air system chilling spiral, and the fire suppression web. The research came to the decision that it is possible to use the ceiling radiant chilling panels with the dedicated out-of-door systems. The DOAS is indispensable to cover with one hundred per centum of the indoor latent tonss and, hence, the room dew-point temperatures. When the dew-point temperature is controlled below the temperature of the panel surface the condensation on the chilling panel is non an issue ( Mumma 2003, p627-635 ) .

Simmons ( 1997, p659-666 ) arbitrated the nest eggs of the ceiling radiant chilling panels systems as follows:

• 15 % less concluding cost of installing.
• Reduced fan powers and smaller, more efficient hair-raisers make possible long-run nest eggs.
• Less care cost because there are no filters and minimal moving parts.
• Balancing and proving are cheaper and less hard to recognize.

The CRCP have an advantage in room infinite, because the ductwork that normally provides all the indoor room with reasonable chilling burden with 13A°C is non needed. When used in new edifices the proprietor can avoid the disbursal by take downing floor highs of the edifice or adding one narrative for every five narratives in relation to regular buildings.

The relation between classical air conditioning and dedicated outdoor air system beaming panel is: it consumes about 29 % of the classical conditioning because of a really small SA and RA sum ; it reduces the chilling spiral 7.6 % yearly ; the energy ingestion is 20 five per centum less because of the decrease of the hair-raiser with the energy recovery can salvage up to forty two per centum of the one-year sum energy ingestion in relation to conventional all air VAV.

All described above shows the specific merchandise of the DOAS, but is adequate to show the capacities on cut downing the sum of energy ingestion by the DOAS in combination with the beaming panel chilling system. It is shown that this combination of air conditioning consumes more pumping power in relation to traditional air conditioning because it is required to accomplish the circulation through the beaming panels. However, the lessening of energy ingestion in fan and hair-raiser which comes from the energy recovery is more of import than the addition in the power for pumping ( Mumma Stanley 2011, p635 ) ,

Building demands

Quality of the Air

In a conference of the United States Department of Health and Human Services in 2009 it was reported that in 20 five per centum of the unwellnesss worldwide that can be prevented, the chief cause is hapless environmental quality of the air, and that taint is besides one of the grounds for 50 thousand premature deceases. The bad quality of air inside edifices is the chief cause of these jobs.

The chief causes for bad indoor air abode quality are:

• Average building and design.
• Bad status of the air conditioning or heating systems,
• Sustainable design in edifices ( insularity and enclosure ) ,
• The usage of man-made coating, stuffs and chattels.

As mentioned in chapter two, minimising the filtrations and isolation in the skeleton of the edifice is of import because this blocks the temperature to accomplish better indoor temperatures and temperature loss, and besides avoid H2O leaks and command the humidness to guarantee a proper circulation of the air and avoids dead musca volitanss which are the causes of cast, elevated allergens, and big sums of interior wet from uncontrolled humidness and H2O leaks.

The sum of contaminated indoor air in a residential edifice is about two to 100 times more than the 1s out-of-doorss in publications made by the United states section of wellness and homo services 2009. Building contraptions, stuffs, furniture and cleansing merchandises are one of the most common contaminations. Well stray edifice building and air tight sealing have at the same clip a job because they tend to barricade fresh air coming indoors. Sometimes they besides promote noxious and unacceptable olfactory properties.

Buildings designed with a snug construction in order to continue energy losingss are inclined to show more jobs in the air quality than edifices with a light skeleton ( sometimes called leaky edifices ) , which the sum of contaminated indoor air does n't travel out of the edifice. Besides, filtration in edifices makes it impossible to command and mensurate the air that goes to the interior through different gaps.

The solution to better the air quality is to diminish the beginning of pollution and increase airing. There is no difference between air quality in places and residential edifices but, however, people populating in residential edifices can non do utmost alterations in airing that people populating in a individual household place can. However, there are different ways to do alterations, like clear the beginning of natural air or usage Windowss to guarantee the entryway of fresh air.

Old edifices that have had preservation belongingss or contraptions good installed and efficient places can accomplish good criterion air quality, because a batch of contaminations are blocked from traveling inside the edifice and the 1s that go indoors subsequently can be removed with the dedicated out-of-door air systems ( DOAS ) described in the old chapter. Buildings with these features soak out the high degrees of wet and their skeleton ensures that contaminated air does non travel indoors. Low breathing stuffs and furniture are besides employed to guarantee a proper degree of pollutants.

In humid climes, the occupants ' most common wont to cut down the cost of energy ingestion is to turn the air conditioning off during weekends and at dark. This pattern is normally the chief factor in the creative activity of wet in these types of climes. Infiltration will take a big sum of out-of-door humidness that will acquire soaked by flat stuffs and constituents when the air conditioning is turned off. In add-on, little degrees of chilling tonss do non let the machine to run at appropriate velocity to be able to soak out the air humidness every bit good as the humidness soaked by the edifice constituents. High degrees of condensation and wet concentration will put on debatable countries if the dry bulb temperature during working clip is sufficient.

Degrees of around 70 per centum of comparative humidness can do mold growing inside a edifice in 24 to 48 hours ( United States Environmental Protection Agency 2010 ) . Rather than the indoor air temperature, surface temperatures inside the edifice are in close relationship with mold growing, but these two temperatures are wall to palisade in relation. Mold causes immense injury to the indoor air quality and besides to the edifice 's lastingness ; hence, it should be closely monitored.

When it comes to footings of air conditioning, means that the edifice does non hold natural airing or a connexion with outside air, hence all its constituents should work independently from the outside temperature and clime, with the exclusion of the machine employed, and when a room needs natural airing, consideration should be taken to guarantee no losingss in efficiency.

In hot humid climates the figure of people busying the indoor infinite sets the guideline as to the sum of airing required to guarantee a proper air-conditioned inside. In large suites such as life suites or dining suites, merely fresh air with disposal or remotion would be required, and in other instances the recirculation of air would be an option when there is a low sum of residents and merely a small fresh air is indispensable.

Electro inactive precipitation filters are in most instances the most efficient 1s which are inexpensive to run and really good in taking away all types of air solid drosss but are a small spot expensive in initial cost. These types of filters are the lone option to filtrate the air in industrial procedures. Other filter options are fabric, syrupy and street arab.

Comfort zone

The indoor temperature of a edifice is profoundly affected by local clime. Solar incursion through Windowss and solar heat gained through the edifice skeleton heat the edifice all twenty-four hours long. To accomplish an indoor liveable temperature it is necessary to take down the interior temperature in relation with the out-of-door one by using inactive methods, air conditioning or a combination of both.

When it comes to soothe by the temperature in a edifice, the indoor air temperature is non the most of import point to take into consideration, alternatively the local physical and climatic elements should be taken as a focal point. Inside the edifice the heat exchange by the tegument of its residents is of singular value due to chill and warm countries and the Sun radiation exposure. Humidity and air motion besides affect indoor thermic comfort in hot-humid conditionss, because the difference in temperature from outside in relation with the interior varies a batch. Normally when outside temperature is 30 six grades Celsius people tend to plan air conditioned thermoregulator around 17 grades, which is a large daze at the minute person enters or goes out of an air-conditioned edifice. Human existences come ining a learned infinite coming from a wholly different outside ambient will happen the indoor 1s really uncomfortable for about one hr ( Dorsi & A ; Krigger 2004, p48 ) .

Humidity control is the chief challenge to accomplish a comfort zone in tropical humid climes, when 50 per centum comparative humidness is the end. Levels normally change in little sums which do non let the systems or machines to take a breath. This was a job before because people avoided the usage of mechanical airing to cut down the sum of wet due to the expensive cost, doing it about impossible to accomplish an indoor comfort zone. This is possible now to accomplish with mechanical airing as mentioned in old chapters without holding excess costs.

Physical environment is the get downing point of the comfort zone in a edifice, which is straight structured by: visible radiation, noise, temperature, humidness and odor. In this thesis humidness is traveling to be studied farther, because of the importance in hot-humid conditions states like Panama.

Residents in office edifices are more productive in their work when the atmosphere temperature is comfy. Accidents occur more when the indoor temperature goes outside the scope of 16 to twenty four grades Celsius. Nevertheless, humidness is closely linked with temperature when it comes to soothe zones.

Normally it is misunderstood that the air impacting comfort is the 1 scaled by humidness metres and thermometers ; alternatively, it is the air that gets in contact with residents teguments. This air will lift and be substituted with other air as it is warmed by the heat in people 's tegument heat. A manner to do the chilling of the organic structure and vaporization of sudating more efficient is by traveling off the air rapidly by natural zephyr or fans, because the addition in vapour of sweat, increases the uncomfortableness.

Recommended indoor air temperature ( OSHA ) should be maintained at 20 to twenty four point five, with a comparative humidness from 20 to sixty per centum and a dew point temperature from minus four until 15 grades Celsius.

At low degrees of dew point about 10 grades Celsius, working together with decreased indoor temperatures, the organic structure needs minor chilling. Low degrees of dew point work truly good together with elevated temperatures, merely as outstanding low humidness of the air licenses effectual chilling.

Temperature is easier to experience by worlds than the sum of humidness in the air, hence people inside a edifice bash non be given to comprehend unwanted degrees of humidness from a temperature criterion. In hot-humid climes the basic response to high degrees of wet inside a room is to take down the thermoregulator of the air conditioning, which increases the sum of energy and makes more likely the overcooling and cast growing because of wet canals.

The sum of Co2 concentration besides has an of import focal point point in a room, which depends on the undermentioned factors: measure of residents, volume of the room, activities of the residents, sum of clip people are inside the room, and the sum of fresh air traveling to the inside. This is more likely to go a job in office edifices, mills and infirmaries, but for abodes where the sum of residents and countries are really low this is non a large issue.

Integrating Advance Humidity Control to Reduce Energy Use

The National Center for Energy Management and Building Technologies ( NCEMBT ) did a study about incorporating advanced humidness controls to accomplish nest eggs in the energy measures, where eleven different system combinations where studied ( see figure 25 ) . ( Harriman, Plager & A ; Kosar DR 1997, p15-25 )

Figure 13: 11 Combination of systems for enhance dehumidification.

All systems presented in figure 25 to carry through the existent heat content decrease in the process, use the conventional DX chilling spiral. The impact of chilling and at the same clip utilizing elements to alter the spiral capacity from reasonable burden to latent burden, consequence in diminishing the reasonable heat ratio of the system.

As the systems that utilize desiccant dehumidifiers downstream alternatively of upstream chilling spirals, needed child system capacity and less sum of energy, merely three of the systems showed above were taken for farther surveies: figure five, six and eleven without optional energy money changer. As the focal point point of the probe was assorted and individual way air systems, DOAS and double systems ( three, seven and eight ) were non taken into consideration.

Combination figure five ( HX-DX ) utilizes a reasonable heat money changer rounding the chilling spiral, which in order to take down the temperature of the air coming indoors, utilizes the air traveling out of the chilling spiral as a heat sink, doing it possible to take down the setup dew point, hence cut downing the reasonable heat wireless. Apparatus dew point represents the release degree of humidness from a system. It shows if a machine without lift in the air flow needed to accomplish the reasonable burden can run into the latent burden.

Combination figure six ( DD-DX ) had similar consequences but using an heat content money changer, due to the latent and reasonable energy money changers, before traveling inside the chilling spiral, the humidness of the air traveling interior is soaked out every bit good. This excess dehumidification decreases the setup dew point in comparing with combination figure five.

Combination figure eleven ( DX-DD ) decreases the dew point ( DP ) of the air in the chilling spiral to accomplish even less apparatus dew point and reasonable heat wireless by using a desiccant dehumidifier. In comparing with the other combinations, its reasonable heat ratio does non cut down with airflow velocity. The desiccant dehumidifier in this system can convey out a dew point near zero grades Celsius and decreases or avoids the congealing of the chilling spiral, which in a traditional DX system happens. The drying agent besides has a disability change overing the latent burden or wet into reasonable heat, which is liberated into the provided air.

Traditional machinery with a DX spiral managed by a thermoregulator is non capable of bring forthing the little sum of reasonable heat wireless which is indispensable in hot-humid climes to accomplish the humidness loaded aerating tonss.

In tropical climes where the usage of specialised and intense humidness controls is needed, this combination of enhanced humidification works with a lower sum of energy power. Lowering energy public presentation even more is possible by utilizing double way DX machines in combination with dedicated out-of-door air systems, conditioning twosome with a degage DX spiral for residuary chiefly reasonable ratio chilling and residuary one.

Functionality

High humidness degrees in tropical climes make it about impossible to accomplish a good quality of indoor air in a room ; air conditioning the bulk of the clip merely cools the outside air but does non take attention of commanding humidness. The systems employed to cut down the degree of humidness in the air should non increase the sum of energy ingestion, because people would non desire to use these machines, even though the quality of the air it is non the appropriate 1.

Bad planning in the airing of a room even with new machines and mechanisms before residents move in, consequences in a bad quality indoor air which does n't suit the criterion demands for the residents ' wellness and besides amendss the construction of the edifice. From the get downing the predesigned ends should be taken earnestly in sing the planning, to accomplish besides good degrees of energy ingestion.

Before an old edifice is adapted into usage, all the airing elements should be checked in all locations to avoid any future jobs, which subsequently on would be hard and really expensive to rectify. Afterwards when the edifice is occupied it must acquire care frequently to look into the operation of the airing systems by supervising degrees of the temperature and quality of the interior air and the air watercourse in every room. Ventilation ducts besides have to be cleaned frequently ( Christensen, Fang & A ; Winkler 2011, p67 ) .

The alterations in edifice demands such as insularity in walls, roof and edifice skeleton, Windowss, contraptions and illuming have made a important alteration by diminishing the heat tonss of interior suites and accordingly the necessities for reasonable chilling. On the other manus, the elements which impact the latent burden or humidness, like airing demands and residents stay the same. Buildings that meet these demands the bulk of the clip need systems to work on the latent burden alternatively of on the reasonable burden.

Bad control in the humidness is linked many times to the inability of traditional air conditioning to pull off the wet loads. The more the efficiency in modern air conditioning, the less its capableness in wet remotion.

Air conditioning does the cooling, it reduces the temperature of the air or reasonable chilling and at the same clip lowers the humidness in the air or latent chilling by distilling a per centum of the concentration of H2O in the air. A manner to mensurate the degree of effectivity of a system to get by with wet remotion is by the reasonable heat ratio, which is the entire chilling capacity of reasonable and latent burden. Lowering the reasonable heat ratio increases the capacity of dehumidification or chilling capacity ( Christensen, Fang & A ; Winkler 2011, p88 ) .

Traditional air conditioning systems normally deal with the reasonable burden before the latent burden, therefore the indoor infinite degree of wet goes up from the one wanted, which is about 50 to sixty five per centum, doing the proliferation of bacteriums and mold growing.

The best manner to accomplish good airing and air conditioning systems in hot-humid climes, is by utilizing the edifice and machines as designed and doing possible the comparative humidness to modulate when the designed infinite status is accomplished. Making possible the air conditioning to cover with the latent and reasonable burden individually consequences in doing it possible to cut down the sum of energy ingestion.

Simulation in TRNSYS

Building description and activity agendas

The office room is confronting north/south ( 29m broad, 29m long ) with a individual glaze window covering the full frontage South. It has 841m2 of country and 3.70m of tallness.

As an office, it has machines, computing machines and unreal visible radiations chiefly during working hours.

Description of the cooling-dehumidifier system

Some trial were made utilizing conventional air conditioning system dwelling on: fans, heat pump, soaking up hair-raisers and dehumidifier chilling spiral, but high sums of energy usage were found, due to the chilling spiral has to cover with high degrees of humidness and at the same clip accomplish temperature needed. Sometimes by altering the sums of indoor H2O temperature and flow rate of H2O, the comparative humidness was achieve by 50 % but the supply air temperature was below the criterions.

A new system was employ using the theoretical account of a dedicated outdoor air system ( Mumma 2001 ) . An heat content and a reasonable wheel were employed to accomplish 2 points of transportation of energy between supply and exhaust air coming in frontal waies. On the Enthalpy wheel ( effectivity of 80 per centum ) exchange of reasonable and latent burden energy occurs, by the transportation of heat and humidness between the supply and exhaust air.

As mentioned above the system decrease the chilling demand of the chilling spiral, by cut downing the degrees of humidness and temperature before it goes inside the chilling spiral. Cooling spirals was designed to take more the degree of humidness at 13 grades Celsius dew point. After the supply air was treated by the chilling spiral it goes inside a reasonable wheel with 70 per centum effectivity where it temperature goes down at around 20 one degrees Celsius dry bulb by soaking up the hot from the exhaust air. This exhaust air decreases its temperature in the reasonable wheel and when it goes back to the heat content wheel aid to chill the fresh air coming in to the inside.

Room simulation and consequences

One simulation was made in November, which is one of the months with highest degrees of humidness due to the start of the rainy season, to mensurate the dry bulb and moisture bulb temperature come ining and traveling out from one constituent to a the following

Taking as an mean outside dry bulb temperature of 29 and outside air wet bulb temperature of 24 grades Celsius. Estimating the system would be working for 720 hours and uses 10,000 cfm.

After the system was modeled all twelvemonth to cipher the sum of energy usage by each constituent of the system ( see table 12 ) .

The exhaust air is estimated to be 90 per centum of the supply air and the supply air achieved was about 22 grades Celsius and 55 % comparative humidness.

By a usage of 8 hours a twenty-four hours Monday to Friday generates a monthly energy usage of 2544 kWh. Panamas mean cost per kWh is.20 cents of Dollar.

Decision

Due to the roar in its building sector in 2008 and its turning economic system, international imperativeness started naming Panama as the "new Dubai of the Americas. '' ( the economic expert 2011 ) Although this fast development has shaped Panama 's beautiful skyline, it did non include much green building.

Consequently, sustainable edifice design is greatly needed in Panama City, where important energy is consumed by residential and commercial edifices, the bulk of which are air-conditioned 24/7 and use floor-to-ceiling individual glass Windowss.

Human comfort is straight related to temperature and humidness degrees. Peoples inside a edifice tend to be more comfy when air is dryer and marginally warmer than when the air is cooler and humid. Increased humidness leads people to take down their thermoregulators because moist air gives the esthesis of a heater ambiance.

This thesis showed the tight relationship between temperature and dew point temperature, which must be considered when planing air conditioning systems for hot-humid climes.

To better air conditioning systems, applied scientists should understand the factors that affect indoor temperature. In these climes, the big difference between outside air temperatures ( ~37A°C ) and thermostat-controlled interior temperatures ( ~16A°C ) -a alteration of ~21A°C-shapes urban air-conditioning design.

Promenades, offices, eating houses and places must use electricity to bridge this spread in temperature, which besides affects the wellness of edifice residents and filtration of incoming air. Changeless alterations in temperature as people go between indoor and out-of-door environments may bring on sweat due to high out-of-door humidness degrees, and may take to respiratory and pneumonic jobs.

The difference between interior and outside temperatures critically affects both A/C burden and edifice construction. Although most systems are designed to accomplish higher indoor air force per unit area than a edifice 's surrounding environment, escape of out-of-door air into conditioned suites can be greatly affect indoor humidness.

Unintended escape is normally due to opening and shutting of Windowss and leaks in the edifice construction, which may take to badly draughty insides. Structure filtration can be reduced through excess attention during the building and usage of such building stuffs as double-glazed Windowss. Air-locks or air-tightness between A/C and non-A/C infinites is a good manner to diminish filtration through doors. Where temperature differences are little, vapor blockers may be utilized in outer walls.

Parameters for simulations to happen an optimum system for a peculiar humidness degree and temperature ca n't be found in surveies of the specific metropolis sing energy usage, building stuffs, air conditioning types, and indoor air features by constructing type. A chilled H2O chilling spiral simulated with a dynamic mold tool ( TRNSYS 17 ) achieved coveted indoor criterions for humidness but delivers a degree of temperature below the criterions ( ~23A°C ) , increasing the energy usage by the chilling spiral so much.

After a Dedicated outdoor air system was analyzed with Panama City clime conditions, accomplishing really good degrees of humidness and temperature criterions

Ideally, criterions for high humidness control could be implemented in the Panamanian building and airing codifications, to make consciousness and execution of good indoor air quality.

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