GARBAGE ROOM VENTILATION
The odors emanating from apartment and condominium garbage rooms has been a problem for years and although I honestly think highly of engineers, you cannot continue to design garbage rooms in the same fashion as has been the norm for the last 40 years and expect to get a different result. The first method of exhausting air and introducing fresh air into the room had some effect, however the exhaust fan ran all the time. The amended design added a thermostat to turn the fan off when the room temperature reached set point. Since the rooms were heated with a furnace in the fall, winter and spring the exhaust fan would be off most of the time and when the fresh air did come in it had to be heated. The last time I checked... garbage still continues to smell whether a fan is on or off. The next design modification was to add an artificial scent into the garbage bins and into the air in the room. This fragrance was quite honestly more offensive than the smell of the garbage. The scent that was added had to be regularly replentished and maintained and there was an associated cost of this service. The next design added air conditioning and in some cases, refrigeration to the room in the thinking that cold garbage would not rot or decompose as fast and the odors would be lessened. Surprise, surprise, surprise as Gomer Pyle used to say... The result of this method was cold smelly garbage. When high rise buildings were apartment buildings only, the owner could dictate that no pets were allowed. No pets meant, NO FECES going down the garbage chute to the garbage room. Condominiums and legal rights to pet ownership changed this along with the "Green Initiative" to separate organic wastes from general waste products. On top of all these designs the air that was exhausted invariably wound up exiting the building right near or next to a tenants patio or window generating a constant source of complaints.
Throughout all the changes in design to the room and equipment for controlling the odors there was not one change to the style of the bins that the garbage was collected in. The lids still do not seal tight on full bins that are waiting for pick up and they all seem to leak any fluid waste all over the floor and loading area. When the garbage trucks come by to empty the bins there is a considerable amount of debris that misses the truck during the dump and the sound of the bin lids crashing closed could wake the dead.
The answer to the odor problem was not found in physics, but in chemistry. Everything on our planet has one common link which is DNA. If you change the DNA of any substance it is no longer the same substance. It may look the same but it will be altered. Scientists have found that odors can be eliminated by ultra-violet light in the same manner that mold, viruses and bacteria can be destroyed. Mold can only exist in dark and damp locations. If you expose mold to sunlight it dies. Sunlight is packed with many types of "UV" rays. It took a chemist to determine that "UVV and UVC" were the two types of ultra-violet light that were needed to destroy odors, mold, bacteria and viruses. This discovery brought about the Ultra-Violet Air Purifier. Odor laden air was circulated over the length of an ultra-violet lamp and voila! The odor was eliminated. Eliminated is the key... NOT MASKED. For years we have known that certain compounds such as baking soda and activated charcoal absorb odors and quite effectively. The question is, Why Absorb when Eliminate is better. For reference I did not fail either physics or chemistry in high school, but this still seemed a little bit Sci-Fi, Twilight Zone for me and I was skeptical. I required proof of the claims for odor elimination so I tested a residential version of the UV Air Purifier in my own home. If you have pets, cook your meals at home, paint your walls, varnish floors, smoke, sweat or fart, you have odors in your home. If your kids go to school they have brought home viruses. If you ever had a wet basement, you have mold. The air inside your home is of worse quality than the air outside, but we can't all live in teepees and can't afford to heat or cool multiple air changes in our homes. *Air Wick* and *Febreeze* would be out of business if every home had the unit I installed on my furnace. I was still in need of further proof and installed the same model of unit on my office duct system where I have been known to enjoy a cigar or two when the staff leaves. I was now a believer that this invention was the greatest since sliced bread
and Viagra. When I was called by one of my customers with a garbage room odor problem, I stuck my neck out and offered the commercial model that I had not tried, on the promise that if it did not perform I would take it back and charge nothing for the equipment or labor. I did not have to take it back and I was paid in full. I have since made the same offer to other customers and not had to take one back. The product is made by "Sanuvox" and they have a full range of products from portable units, ceiling grid units for office kitchenettes or washrooms, garbage room units and very large units for large office building cooling systems. All the engineering data and product information can be found on their web site at www.sanuvox.com. I have never had the full confidence in a product to endorse their system until I tested the units myself.
With the addition of the Sanuvox garbage room unit we were able to reduce the speed of the existing garbage room exhaust fan, remove the thermostat that controlled the fan so it would operate 24/7 and completely close the fresh air dampers. The constant exhaust created a negative pressure in the room, but more importantly a negative pressure in the garbage chute and shaft. The negative pressure stopped dust blowing out into residents faces when they opened the chute to dispose of garbage, prevented odor migration back into the halls, outside of the garbage room and stopped the updraft up the shaft that often carried garbage with the up flow of air. The reduction of exhaust air to outdoors reduced the odors outdoors and the energy costs to heat or in some cases, cool the room were reduced because there was less outdoor fresh air infiltration into the room. The scented ENG-TIPS FORUM
I need to cool a garbage room so as to reduce odor due to spoiling of organic matters. What is the internal garbage room temperature I should be designing for? The garbage is taken out once daily, usually at night, to a dump site.
Please indicate which refernece is used to obtain the information from hello,
pls see www.hvacmall.com
i think you will find materisl or help from there also. thanks
There are many ways to deal with odor depending on the types of odor. Human perception of odors is more a function of humidity than temperature; so humidity control is the key here. Likewise is the issue of bacteria growth. Another approach is good ventilation and fresh air intake. I suggest you get a copy of the latest ASHRAE fundamentals handbook and review it as it pertains to your particular situation. There is a chapter devoted to odor control. http://files.engineering.com/getfile.aspx?folder=e6c9b887-ac1a-4115-bf1e-67
I have several island hotel projects with the same requirement. The unit was sized at 150 square feet per ton.
The thermostat is set at 60 deg F. The unit runs 24/7.
The walls and ceiling have R-30 insulation.
Be sure to have a floor drain and a hose bibb in the room to wash the room down everyday.
Thanks, Steve. That's what I like: specific, experience-based information! I'll save your respnse under "garbage, odor control"! -:)
Stevenw
Thanks for the info.
What are the numbers based on ? The numbers are based on experience. Quantum2 -
If the garbage is removed once daily, I wouldn't focus on AC so much as exhaust ventilation. No scientific evidence to back this claim, but bacterial growth between a 60°F room and an 80°F room probably wouldn't be orders of magnitude different in a 24-hour period. With a daily turnaround of trash from this space, a majority of growth might occur at the various points of origin of the trash rather than the dumpster location.
Current standards for exhaust for odorous or potentially hazardous areas is 1 cfm per square foot, and you will want to make up air at about .8 cfm per square foot to keep the space negative relative to surrounding areas. Most of these areas I've seen are in loading docks or areas where room conditions (e.g., open bay doors) would preclude full air conditioning.
I agree with provisions for drainage and a daily wash-down. Ventilation is cheaper than AC.
On my job the trash room backed up to the pool deck so exhausting the room was not an option. hi guys,
Could you please help in calculating head of closed loop system in high rise building.
I am quite confused, as in closed loop piping we dont consider head loss due to elevation(static lift) , i have seen some article on internet in which they have considered some hydro static pressure. In closed loop system, we consider head loss through piping friction,fittings and equipment like chiller,AHU etc.
but in the article they have considered the static lift also. Please guide me on this.
I am attaching the file please see pg 81 chapter-7
thermal lift is calculated, not hydrostatic pressure, as it is significant.
in today's circumstances that is more issue of balancing than pump selection as most of pumps would be variable speed which can cover range from zero thermal lift to nominal design conditions lift. the rule of thumb is to take 50% of calculated thermal lift as nominal condition.
however, if i ever have enough influence on concept design, i would always tend to separate high building into few height zones.
All the various pressures in Figure 7-3 are only looking at pressure changes from various different locations.
In a closed system, once the pipe is full of water - the static pressure on the suction side of the pump is the same as the discharge, no matter where you put the pump because. So when pumping starts, the only thing the pump has to overcome is friction due to pipe, fittings, etc.
Guys Thanks alot for your suggestion.
Drazon- If its closed loop system then why to consider building height in the head. PEDARRIN2- Yup i agree with you, but they have shown the pressure at different level.
I m confused about the theory written in the document and the figure reflecting in the document. Taking a better look at the article and pictures, the authors are indicating the position of the equipment (not the pump) is what is in question for static pressures. Since the reference point appears to be the level of water in the expansion tank, the location of the chiller relative to that location will determine what pressure the chiller will experience. Solution A, with the chiller at the bottom, the chiller will experience the shut off head (140 ft) plus the static (900 ft). This is due to the static pressure exerted by the 900 feet of water in the pipe on the equipment. Putting the chiller at the top, it only has the shut off head (140 ft) and static (10 ft). So it would experience much less static pressure.
Static pressure at the bottom of a riser will always be greater than the static pressure at the top of a riser, so equipment that can only handle lower pressures should not be located on lower floors, unless some sort of pressure regulation is employed.
pedarrin2 - agree. but why are we considering static as it is closed loop system.
what I know that, in close loop system we pipe is full of water and does not consider static lift. in pump head calculation, we need to consider piping friction loss, fitting loss and loss in ahu, fcu and chiller for closed loop system.
correct me if I m wrong or not getting your point. I m jus beginner and will be thankfull to You if you guide me on this.
Equipment and pipe and fittings typically are rated for maximum pressure.
If I use a pipe fitting or chiller that is only rated for 150 psig, I have to make sure that during no flow (static) and flow (dynamic) conditions - that fitting or chiller is not experiencing pressure exceeding its rating.
The article was talking about where to put the chiller.
From the article, "The decision about the level on which the refrigeration machines and the
supporting chilled water and condenser water pumps are located in a building is a decision that can have a cost impact on the refrigeration equipment, the pumps, the piping, and the fittings and valves associated with the piping. The economic impact will be due to the change in the design working pressure to which the equipment, piping, fittings, and valves will be subjected by the system.... The working pressure on any equipment or the piping, valves, and fittings at any location in a building is the sum of the hydrostatic height of the water in the piping above the point being considered plus the dynamic pressure created by the pump at the point being analyzed. The hydrostatic and dynamic pressures are determined in feet of water. Their sum, when added together, is the total pressure or working pressure in feet at the referenced point. To determine the working pressure in PSIG, this total pressure in feet must be divided by 2.31. This is the conversion factor to convert pressure in feet of water to pressure in PSIG."
Using the example, the maximum pressure the chiller would see, if on the bottom floor, is
approximately 900 ft (due to elevation) + 140 ft (due to pump shut off pressure, which is basically the TDH provided by the pump during operation and the shut off pressure of the pump) for a total static pressure of 1040 ft (450 psi) per Solution A. This would exceed the rated pressure of the described fitting/chiller.
If the chiller is on the top floor (Solution C), then the total pressure the chiller would see would be 65 psi. This would be within the pressure rating of the fitting/chiller. The pump is still contributing 140 ft to the pressure, but because of the difference in elevation, the static effect is much less.
In this case you would specify fittings/pipe with higher pressure ratings on the lower floors and decreasing ratings as you went up. You would locate the chiller at a level where the pressure does not exceed its maximum pressure.
I hope that helps.
I didn't read in depth but I think they are showing (in figure 7-3)is the working pressure the chiller will see at different locations. While static pressure doesn't show up in the pump head calculation, it does show up in what the equipment/pipes/devices have to withstand. It also comes into play with expansion tank size (depending on where its located) and relief valve size on equipment as well as pressure ratings of equipment.
Sooooo not rocket science. HVACDomain, you’re right in that the pump has to overcome system friction only. When you first fill the system in a high rise, you have to do it with a pump that can overcome the height head loss. If it’s a 300 ft tall building for example you need a pump with at least 300 ft head. The system’s pump that is designed for 600 gpm pump at 100 ft head won’t do much good until the loop is filled. After the loop is filled, the 600 gpm, 100 ft head pump will do fine to overcome the system friction.
pedarrin2, chasbean1, 1124- thanks guys.
I agree the article is reflecting the effects of pressure on equipment according to the location of chiller and height of building. that's fine.
so, doesn't it effect the pump head calculation.?
1-if a building is 900 ft in height having close loop system, do we consider this 900 ft in pump head calculation? or we consider only head loss in piping and accessories?
2- does height of the building effect the static pressure of the equipment only? it has nothing to do with pump head calculation?
1 - no, unless you use the pump to fill the system, but then it would not be a closed system for that phase.
2 - yes.
Just apply Bernouli's on a closed system: For every foot you 'rise' on the discharge, you have a foot of 'drop' on the suction.. The heights cancel one another.
11241-thanks yeah, agree.
but static pressure doesn't cancel. right.?
and we consider height to check the static pressure at the equipment.
The static pressures at the suction and discharge of the pump in a closed system are equal - so they do cancel.
The static pressures at the suction and discharge of the pump in an open system are not equal, thus this pump has to be sized to compensate for this difference plus friction loss.
hvac domain, as mentioned in high rise building thermal lift is significant and as it is proportional to circle height, height appears in the equation.
you have to calculate it in high rise, with about 30 floors it can already be on level of 15% or more of friction losses.
There is a difference between the pressure required from pump which is generated by the pump itself (dP)and the hydrostatic pressure generated by elevation
the fist one, we considered it for moving the fluid but the second one we considered it for
determining the max. working pressure inflicted upon pipes, pump's parts (casing , mechanical seal ,....)and all the elements in network
example:
If we calculated dP=5bar required from pump to move the water with the required flow rate. these 5bar may be from 1bar to 6bar
and may be from 15bar to 20bar
The 2 cases have the same dP (friction losses and fittings ,....) but not the same max. working pressure
For a closed loop system only friction loss is applicable. no static head because the pressure drop during lift is regained during down flow. No velocity head since there is no remarkable change in velocity.
Timothy-Right, agree with you.
Hatem2014- Hello, Thanks alot for your comment, I just need more explanation and clarifications about it, I have started getting your pint now.
I request you to please describe it briefly , i will be highly thankful to you, also please elaborate how to CALCULATE static pressure to check the pressure in pipe.
Static pressure is always calculated from a reference point, which is typically the lowest level. So if the lowest level is at 0' and the highest pipe is at 900'. Since the system is not open, you have to add the 140 ft of pressure from the pump shut off, so you have 1040 ft (450 psig) at the lowest point point. If you go up to mid height (450'), you would have 450 + 140 = 590 ft (255.4 psig). These are the pressures the pipe and equipment will experience so they have to be rated for those pressures. I have not read the book but I suspect that static head was considered since air will always get in somehow particularly thru shaft seals and ultimately fill the expansion tank if not released.
Yes, this confusion only occurs in the case of closed loop because regaining pressure during down flow as you said
Timothi
But with regard to velocity pressure is not our topic now to avoid more confusion HVACDomain,
Assume we have 150 meters tall building and the pumps installed in zero level then, after finished installation we will fill the network by water
If we take the pressure gauge reading before running the pumps at zero level we will read about 15 bar . the pressure will be the same at discharge and suction line of pump and equal 15 bar.
This pressure is generated by the elevation without running pumps and without moving water means without pressure drop due to friction and fittings , ...
After running pumps we will obtain more than 15 bar pressure at discharge point of pump may be for example20 bar
PEDARRIN2,
You are right, so it is more economic to install equipments in high level as you can because you will need no strong equipments to bear high pressure
For a closed loop system, only frictional loss due to pipe run, valves & fittings is applicable. You can follow "equivalent length method" to calculate total frictional loss in your closed loop system. Sharing knowledge is the best way to learn
