Air is delivered to a room at 58 F and the same amount of air is removed from the room at 76 F in order to provide sensible cooling. The room requires 0.5 tons of cooling to remain at a steady 76 F. That must the aifflow rate be in cfm? sume an air densiW of 13.5 cubic feet per pound mass and a
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Heating, Ventilation, and Air Conditioning: Analysis and Design
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- Calculate the EER rating of a 20 ton (240000 Btu) air conditioning unit with an average electrical load of 30 kW. An air conditioning plant supplies air to a room at a rate of 2.5 kg/s, the supply air being made up of equal parts by weight of outdoor and recirculated air. The mixed air passes through a cooler coil fitted with a by-pass duct, face and by pass dampers being used for humidity control. The air then passes through an after heater and supply fan. In a test on the plant, the following conditions (Table Qu 4) were recorded; 3 Table Qu. 4: Parameters recorded Relative humidity Dry bulb temperature °C Wet bulb temperature °C % Outdoor air 270 20.5 Room air 210 50 Supply air Air leaving cooler 160 11.8 80 90 coil Make neat sketches showing the plant arrangement and the psychrometric cycle and identify the corresponding points on both diagrams. Calculate the following; mass of air through the cooler coil load on cooler coil load on heaterarrow_forwardyour A bank of 120-employees is maintained at 24°C db and 50% RH. The heat gain due to heat transfer through walls, roof, ..etc is 10 kW. The outside air temperature is 35°C and its relative humidity is 60%. Calculate the followings: (a) Ventilation air required. (b) Sensible and latent heat gains due to occupants. (CLF = 0.86) (c) Volumetric flow rate of supply air if the supply temperature is 18°C. (d) Volumetric flow rate of moisture removed. (e) Sensible heat ratio of the theater. (f) Relative humidity of the supply airarrow_forwardHeat is produced by computers while they run. Do you have any questions concerning computer cooling systems?arrow_forward
- what is the heating value of oil in BTU/lbm at 27 degree APIarrow_forwardA summer air-conditioning shown below is required to maintain a certain room at specified conditions. The layout of the system is indicated on the next page and the specifications are listed below.System specifications:Required room temperature: 23⁰C, 50% Relative humidityAtmospheric pressure: 101 kPaOutside air conditions: 30⁰C, 80% Relative humidity Sensible heat gain: 5 kWLatent heat gain: 4 kWTemperature rise across fan: 1.5⁰CTemperature of air leaving cooler: 12⁰CTemperature of air entering room: 18⁰CApparatus dew point of cooler: 7⁰Carrow_forward/ A hall is to be maintained at (20 °C DBT, 60 % RH) when the outdoor conditions are (40 °C DBT, 26 °C WBT). With the following conditions: Sensible heat load in the room Latent heat load in the room 66000 kJ/hr 20000 kJ/hr 30 m/min 5 °C Infiltrated air Apparatus dew point temperature. If the 60 % of the total air is recirculated from the hall and is mixed with the conditioned air after the cooling coil. Find the following: 1-The conditions of air leaving the conditioner. 2- Mass of fresh air entering the cooler. 3- Bypass factor of the cooling coil. 4- The refrigeration capacity of the cooling coil in the tons of refrigeration o 0a DDTarrow_forward
- Heat transfer حسذarrow_forwardA summer air-conditioning shown below is required to maintain a certain room at specified conditions. The layout of the system is indicated on the next page and the specifications are listed below.System specifications:Required room temperature: 23⁰C, 50% Relative humidityAtmospheric pressure: 101 kPaOutside air conditions: 30⁰C, 80% Relative humiditySensible heat gain: 5 kWLatent heat gain: 4 kWTemperature rise across fan: 1.5⁰CTemperature of air leaving cooler: 12⁰CTemperature of air entering room: 18⁰CApparatus dew point of cooler: 7⁰C Draw the processes on a psychrometric chart and determine the following: 1.The ratio of mass flow rate of re-circulated air to the mass flow rate of air supplied to the room. 2.The heat removed by the cooling coil.3.The heat supplied in the re-heating coil. 4.The cooling coil bypass factor.arrow_forward3. Solar radiation heats the surface after sunrise, and the resulting heat flux F to the atmosphere is approximated by 2T(t – tnoon) F = F cos 6 a.m. < t< 6 p.m. max Atarrow_forward
- 3:57 A Done lecture 7_b5ee35c08478147bb8a3744a... Lec. (7) tar -Dry bulb temperature O Example (1): An air conditioning equipment (figure) have the following: - Supply air mass-1.26 kg/s. The cooling coil receives 20 % outdoor air and 80% return air. tdz Fig. 18.14. Representation of supply air condition and room design condition. 0.252 kg/s Refrigeration and A/C - Outdoor air conditions are: 28°C db, 19.5°C wb Return air conditions are: 22°C db, 50% RH. The mixture air condition outlet the cooling coil are: 10°C db, 0.00735 kg/kgda Draw the system on the Psychrometric chart, then calculate: 1. Cooling coil load. 2. Room sensible heat. 3. Room latent heat. 4. Fresh (outdoor) load. 5. Duct and fan heat gain 6. Sensible heat ratio SHR. If the supply air temperature increases with a value 1°K due to fan motor heat gain and 2°K due to duct heat gain. . ← 1.008 kg/s R to Dr. Omar M. Ali LTE الغرفة المراد تكييفها (22,50 %) 1.26 kg/s R Grand Sensible Heat Factor It is defined as the ratio of…arrow_forwardHello Sir,Good Morning.I have a question in my homework related thermodynamics lesson. The following below is my question. Please advice. Thank you. Regards,Irfan An air conditioning system is used to keep the house at 65°F when the outside temperature is 85°F. The house gets heat through the walls and windows at a rate of 810 Btu/min, and the rate of heat generation inside the house from occupants, lights, and equipment is 120 Btu/min. Determine the minimum power input required for this air conditioning system.arrow_forwardQ2 : Room walls are composed of common bricks and outside and inside plaster layers with an overall heat transfer coefficient of 2.5 W / m² ° C . The outside air temperature is 15 ° C ( DBT ) and the inside design conditions are 23 ° C DBT , 55 % RH . Is condensation occur on the inside surface or not ? Take f = 8.26 W / m² ° C . SHIarrow_forward
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