Exchange rate heating and ventilation

Contents

Contents:

1. General part

2. Heat point

2.1. Calculation of heat demand of the building for heating

2.2. Equipment calculation

Heat exchanger calculation

Mud Machine Calculation

Expansion tank calculation

2.3. Hydraulic calculation of heat conductors

2.4. Pump Circulation Pressure Calculation, Circulation Pump Selection

3. Central heating of the building

3.1 Hydraulic calculation of the main circulation ring

3.2 Hydraulic calculation of secondary circulation rings

3.2.1. Circulation ring through riser

3.2.2. Circulation ring through riser

3.2. Thermal Calculation of Heating Appliances

4. Furnace heating

4.1. Furnace Thermal Calculation

4.2. Fuel tank calculation

4.3. Inspection of furnace heat perception

4.4. Calculation of gas velocity in furnace channels

4.5. Furnace Heat Storage Check

4.6. Furnace Heat Transfer Density Check

4.7. Check of air temperature fluctuation amplitude

Bibliographic list

Exchange Rate Project

"Civil

building heating"

General part

Vladivostok construction area.

The name of the object is an administrative building (3 floors).

Heat transfer resistance of enclosing structures:

external walls 2.78 M2 * 0С/W

slabs 0.41 M2 * 0С/W

0.68 M2 * 0С/W windows

ceiling 3.13 M2 * 0С/W

Floor heights:

1st floor 3.6 m

2nd floor 3.6 m

3rd floor 3.6 m

height of ground elevation 0.9 m

basement height 2.5 m

Window dimensions: 1.6x2.1 m and 2.4x2.1 m

Dimensions of entrance doors: 1,6x2,1 m

The main facade faces south.

Climatic characteristics of the construction area. As per SNiP 23.0199 "Construction climatology"

The average temperature of the coldest five-day coverage is 0.92 - t1 0.92 = 24 0С;

The average temperature of the coldest days with a security of 0.92 - t1 0.92 = 26 0С;

Average heating season temperature (period with average daily air temperature < 8 0С - tot. Per. = 3.9 0С;

Heating season duration - Zot.per = 196 days.

The estimated wind speed for the cold period, which is the maximum of the average rumba speeds for January, the repeatability of which is not lower than 16%) - Vn = 13.5 m/s;

The source of heat supply is the urban thermal urban network.

The coolant is water, with a temperature in the supply pipeline tg = 95 ° C, and in the return pipeline to = 70 ° C.

Two heating systems are designed in the building: a double-tube heating system with lower piping, with associated water movement in the highways (heats the administrative and therapeutic parts of the building) and a horizontal heating system, with associated water movement in the highways (heats the boxes for ambulances).

In the double-tube heating system, heating devices are designed: cast-iron sectional radiators of the MS140AO series with top-down access to the device. In the horizontal system, heating devices are designed: smooth tube registers.

Heat point

Calculation of heat demand of the building for heating

rooms (when laying both lines in the technical subpole or basement k = 1.03; when laying one of the lines in the attic k = l, l), we accept k = 1.03;

Qdd - design heat loss of heated building, Qdd = 127320 W;

β1 - coefficient of accounting of additional heat flow of heating devices due to rounding of their area in excess of the design value, we accept β1 = 1.04; as per Table 1, Appendix 12 [1]

β2 - coefficient of accounting of additional heat losses by instruments located near external enclosures is taken as β2 = 1.02; tab.2, enc. 12,[1]

, W.

Design water temperature.

Water temperature in the giving highway of thermal network: T1 = 150 wasps.

Water temperature in the return highway of thermal network: T2 = 70 wasps.

Water temperature on heating login: tg = 95 wasps.

Water temperature on heating leaving the system: to = 65 wasps.

Total water consumption in the heating system.

, kg/h, (2)

where:

Qc - Design heat consumption of the building heating system, Qc = 139110 W;

with - the specific heat of water, with = 4.2 kJ/kg of wasps;

tg is water temperature on login of heating, tg = 95 wasps;

to is water temperature on leaving the system of heating, to = 65 wasps;

kg/h.

The diameter of the pipes at the thermal point is taken into account that at this flow rate the water velocity in the pipes will be 1... 1.5 m/s, we select the pipes 40 mm, the speed will be w = 1 m/s, the specific pressure loss is R = 480 Pa.

The heating system is connected to the heating network according to an independent scheme, a high-speed water heat exchanger according to OST 3458868 is used as a water heater. Required heating water flow rate is determined by formula similar to formula (2):

kg/h.

By value A we select heat exchanger as per tab.14.14 [13] and determine its main design characteristics:

heating surface area - A1 = 1.11 m2;

length of one section - l1 = 2 m;

number of sections - n = 5;

outer diameter of tubes - dn = 0.016 m;

internal diameters of tubes - dv = 0.014 m;

number of tubes in one section - Z1 = 12;

area of live section of tubes - ftr = 0.00185 m2;

annulus area - fm.tr = 0.0026 m2;

internal diameter of heat exchanger housing - DB = 0.082 m.

Actual heat transfer coefficient of the heat exchanger:

W/m2 OS.

Actual heat transfer capacity of the heat exchanger:

W .

The required Qto margin with respect to Qc shall be at least 10%, margin:, the heat exchanger is selected correctly.

Pressure losses in the annulus of the heat exchanger:

Pa, (7)

where:

A - coefficient depending on the heat exchanger design, A = 0.54 as per tab.14.16 [3].

Pa.

Actual diagram of heat point in axonometric projection on sheet 7.

Mud machine calculation.

We select the mud maker by the diameter of the supply pipes. If the diameter is 40 mm, accept the heat exchanger as per ORGRES data.

Diameter of supply pipes - Dy = 40 mm;

casing diameter - D = 216 mm;

housing height - H = 350 mm

height from the bottom of the housing to the axis of the guide pipe - h = 275 mm

partition height - L = 175 mm

wall thickness - S = 15 mm

length of supply pipes - C = 120 mm

The speed of water in the mud machine shall not exceed 0.05 m/s. It is determined by the formula: m/s, which is less than 0.05 m/s. The mud truck is right.

Central heating of the building

3.1 Design of heating system diagram.

Two heating systems are designed in the building, since there are two buildings in the building: administrative and car boxes. In the administrative building, a double-tube heating system with lower main lines and associated coolant movement in the heat pipeline is designed. In the car boxes, a horizontal heating system with associated water movement in the highways is designed. Heat conductors are laid under the slope i = 0.003 towards the heat point. The supply line is covered with thermal insulation, the return line is not isolated and is used for basement heating. Air from the system is removed using Mayevsky cranes installed on the devices of the last floor. Control valves: double control valve are installed in front of the instrument

Hydraulic calculation of the main circulation ring.

The main circulation ring (BCC) is selected in the longest and most loaded part of the system, where the specific friction pressure losses have the lowest value.

We choose the CCC through the 13th riser.

, Pa/m

Actual pressure losses in the heating system are determined by the formula of the same formula (10):

Pa . (13)

For convenience of calculation by breaking (BCC) into sections (heating system pipelines with constant water flow rate), we calculate pressure losses separately in each section. Water flow rate in the section is determined by formula similar to formula (2):

, kg/h. (14)

Friction pressure losses are found from Annex II, Table 1, [2].

Local resistance coefficients are found according to Annex II, Table 1220, [2].

Z is found by the sum of PBC in the section and as per Table 3, Annex II, [2].

Results of calculation of BCC by specific pressure losses are summarized in Table 1.

The pressure margin must be 5... 10%, determined by the formula:

3.3 Hydraulic calculation of secondary circulation rings.

In case of associated water movement, rings are selected on highways through the first and far risers.

When calculating secondary circulation rings (WCC), only areas not included in the WCC are taken into account. Calculation of WCC sections is similar to calculation of WCC. The total pressure losses in the calculated sections of the AAC are compared with the value ΔPr.vtc - the available pressure in the sections of the ACC:

, Pa, (16)

where:

(Rl + Z) 1 - total pressure loss in the BCC sections hydraulically parallel to the design sections of the BCC.

Non-binding is determined by the formula:

. (17)

The resulting deficiency should not exceed 5%.

3.2.1. Circulation ring through riser 1.

In the calculation of the circulation ring passing through the riser 1, sections 23 to 30 are involved. Available pressure in the AAC sections:

Pa.

Results of WCC calculation through the 1st riser are summarized in Table 2.

Non-binding:

3.3.2. Circulation ring through riser 19.

In the calculation of the circulation ring passing through the riser 1, sections 31 to 41 are involved. Available pressure in the AAC sections:

Pa.

The results of the calculation of the RCC through the 19th riser are summarized in Table 3.

Non-binding:

Figure 1 shows the diagram of circulation pressure distribution in the lines. Built in accordance with recommendations

The actual density of heat flow on the surface of the heating device is determined by the formula:

Rounding the fractional number N to the integer is carried out upwards.

The area and number of elements are calculated for all heating devices of the heating system. The results of thermal calculation of instruments are listed in Table 4. For horizontal system instruments, the number of elements is determined approximately by averaged heat flux density values using detailed calculation data.

4. Furnace heating.

4.1. Furnace design and size.

Let's place the oven in room number 126 on the first floor. The room has a plan size of 6.0x4.2m, a height of 3.6m, triple windows with an area of ​ ​ 8.82 m2, an internal door, an area of ​ ​ 1.8 m2 Qp. = 1888 W We choose an OPT1 furnace with Q = 2000 kcal/h. The furnace is made of clay ordinary and refractory bricks (336 pcs).

As a grid, a grate of 25x252 mm is used. The average heat dissipation capacity of the walls is:

front - 400 W;

- rear - 400 W;

RH - 600 W;

LH - 600 W

Furnace fuel - coal near Moscow with Qnr = 12600 kJ/kg. Furnace has coefficient M = 0.4.

4.2. Calculation of the fuel tank.

Required height of fuel tank is determined using dependence of specific thermal stress of fuel tank volume Qt/Vt, W/m3 on type of fuel.

Hm = G * Qnr * ¼ m * (3.6 * m * Apod. * [Qm/Vm]), m, where

¼ m - Fuel tank efficiency, which takes into account incomplete combustion and failure of part of the fuel into the ash (for grate grate, ¼ m = 0.9)

m - furnace duration (for coal m = 1.9 h)

Qm/Vm - allowable specific thermal voltage of fuel tank volume, Qm/Vm = 440000 W/m3 .

Qnr - lower fuel combustion heat, Qnr = 12600 kJ/kg.

G - fuel consumption during one furnace of the furnace.

G = 3.6 * Qp * (m + n )/( Qnr * ¼ n), kg/h, where

Qp - design heat loss of the room, Qp = 1888 W

n - furnace cooling time n = 12 m = 121.9 = 10.1 h;

¼ n = Furnace efficiency (¼ n = 0.7).

G = 3.6 * 1888 * 12/( 12600 * 0.7) = 11.3 kg/h

The design area of the furnace hearth is determined by the formula:

Ak.p = G/( m * Bp);

Bp - allowable specific stress of grate, kg/( h * m2)

Ak.p = 11, 3/( 1.9 * 120) = 0.05 m2, which is less than the actual value of 0, 255x0.242 = 0.06 m2.

Find the height of the fuel tank:

Hm = 11.3 * 126000 .9/( 3.6 * 1.9 * 0.126 * 440000) = 0.75 m.

Keep the fuel tank height unchanged. The speed of air movement in the basement hole is determined by the formula:

Vg =G*Lo * (1+tv/273) / (3600*m*akan), m/s, where

tv of =21 °C

Lo - air volume practically required at its temperature of 0 ° C and normal atmospheric pressure for combustion of 1 kg of fuel, m3/kg Lo = 12 m3/kg, Akan - cross-sectional area of ​ ​ channels/blowing hole, m3, Akan = 0.14 * 0.13 = 0,0182 m2.

Vg = 11.3 * 12 * (1 + 21/273 )/( 3600 * 1.9 * 0,0182) = 1.9 m/s.

The air velocity is within acceptable limits.

4.3. Inspection of heat perception of the furnace.

For the period of time from the beginning of one furnace to the other, the total amount of heat, Qtl, kJ, equal to the heat losses of the room for this period shall be transmitted from the furnace: Qtl. = 3.6 * Qtp * (m + n) = 3.6 * 1888 * 12 = 99661.54 kJ.

According to the drawing, we will find the area of ​ ​ the internal surface of the fuel tank and the gas ducts of the furnace .

Fuel tank:

Gas speeds are within acceptable limits.

4.5.Verifying furnace heat storage.

The furnace shall accumulate the amount of heat:

Qacc.tr. = 3.6 * Qp * n = 3.6 * 1888 * 10.1 = 83881.79 kJ

Active furnace volume:

Va = 2.38 * 0.51 * 0.77 = 0.93 m3

Furnace cavities volume:

-in fuel tank - 0.65 * 0.63 * 0.27 = 0,10546 m3

-in pressurized - 0.16 * 0.16 * 0.12 = 0,00307 m3

-in the 1st gas duct - 0.12 * 0.72 * 0.27 + 0.28 * 0.17 * 0.27 + 0.14 * 0.36 * 0.27 + 0.13 * 0.13 * 0.27 = 0.07512 m3.

-in the last gas duct - 0.96 * 0.13 * 0.27 = 0,0337 m3

∑Vpol.=0,27169 m3

Actual Furnace Battery:

Qakk. = (VaVpol.) * αm * cm * Δt, kJ, where:

αm is the density of the array. kg/m3 (for brick 1800 kg/m3).

cm - mass heat capacity, kJ/( kg * ° С) (for brick 0.7 kJ/( kg * ° С)).

Δt - average change of array temperature, ° С, Δt = 80 ° С.

Qakk. = (0,930,27169) * 1800 * 0.7 * 80 = 79357.64 kJ

Δ = 100% * (83881,7979357,64 )/83881.79 = 5.3%, which corresponds to the permissible deviation 15%.

4.6.Check the heat transfer density of the furnace.

The following condition shall be met:

Qp. = q * Act, W, where

Q is the average heat transfer of 1 m2 of the active surface of the furnace, W/m2.

Aact. - area of the furnace heat removal surface, m2 within the active height. The calculation takes into account not only the area of ​ ​ the open surface of the furnace, but also the side surface facing the indentation (with a coefficient of 0.75 with narrow and laterally closed indentation).

Act. = 2.38 * 0.92 + 2.38 * 0.53 + 2.38 * 0.92 * 0.75 + 2.78 * 0.53 * 0.75 + 0.92 * 0.53 * 0.75 = 4.38 m2.

Q = Qp/Act = 2000/4.38 = 456 W/m2.

Is within acceptable limits.

4.7.Verifying the amplitude of air temperature fluctuations.

Determine the amplitude of air temperature variation in the room:

At=0.7*M*Qp/(∑ (Bi*Ai) of ≤3 °C, where

M is the coefficient of uneven heat transfer of the selected type of furnace.

B is the heat absorption coefficient.

∑ (Bi * Ai) is the sum of the products of the heat absorption coefficient of the i-th absorbing structure of the room on the corresponding areas of these barriers.

At = 0.7 * 0.4 * 2306.98/( 2.67 * 9 + 7.04 * 74.37 + 2.9 * 1.8 + 9.76 * 45.1 + 5.86 * 45.1) = 1.3 ° С < 3 ° С

The value of vibration amplitude is within the limits of the norm.

Output: The furnace is suitable for use as the heating unit of the selected space.

Bibliographic list

SNiP 2.04.05 - 91. Heating, ventilation and air conditioning. M.: TSITP, 1998.

Internal sanitary facilities. At 3 h. Ch.1. Heating/Under ed. I.G. Staroverov. - Ed. 4e, M.: Stroyizdat, 1990

Installation of internal sanitary devices/Yu.B. Alexandrovich et al.; Ed. I.G. Staroverov. - Ed. 3e, M.: Stroyizdat, 1984

Theological V.N., Skanavi A.N. Heating: Textbook for universities. M.: Stroyizdat, 1991

Semenov L.A. Furnace heating. - Ed. 3rd. M.: Stroyizdat, 1968

A.N. Skanavi, L.M. Makhov, Methodological instructions for the implementation of course and diploma projects.