Coursework Heating and ventilation of a 3-storey residential building

Contents

Contents

Leaf

1. Design Input

2. Thermal engineering calculation of external enclosing structures of the building

3. Calculation of heating plant and building capacity

4. Choice and design of heating system

5. Hydraulic calculation of water heating system

6. Heat engineering calculation of pipes and heating devices

7. Calculation of the main equipment of the individual local

8. heat point

9. Selection and design solutions in the natural ventilation system

10. Aerodynamic calculation of natural ventilation system

11. Literature used

Izhevsk State Technical University

Department "Hydraulics and Heat Engineering"

EXPLANATORY NOTE

To the course project "Heating and ventilation of a 3-story residential building"

by discipline

"Heat and

gas supply and ventilation"

Design Input

Heating and ventilation systems are being designed in a three-story residential building. Construction is underway in the city of Arkhangelsk. The building is brick, with a floor height of 3 meters. The heating system centralized with a temperature of heat carrier of 15070 wasps. Entry into the building is carried out through the basement, the height of the basement is 2 meters.

Heating period duration Z = 253 days.

Temperature of external tn air = 31 wasps

Average temperature of the heating period of tn = 4.4 wasps

Temperature of internal air zh. to. tv = 20 wasps

Temperature of internal air angular zh. to. tv = 22 wasps

Temperature of internal air of kitchen of tv = 18 wasps

Temperature of internal air of l. tv m = 16 wasps

Thermal engineering calculation of external enclosing structures of the building

2.1 Heat engineering calculation of the outer wall, floor above the basement and floor above the last floor.

°1. Required thermal resistance to heat transfer of R0TP enclosing structure.

Calculation of heating plant and building capacity

Heat loss in the building premises is determined by the following formula:

Choice and design of heating system

The building has designed a heating system with lower wiring (laying of supply lines along the basement), single-tube (water is supplied, and the device is removed from it by one riser, the devices are connected in series along the coolant), vertical. The heating system is centralized. Water is used as coolant, with the following parameters:

- for heating system:

falling line - t = 95 С, reverse line - t = 70 С;

- for heat networks:

falling line - t = 150 С, reverse line - t = 70 С.

Instrument connection diagram - straight-flow - adjustable with offset closing section. The direction of water movement in supply and return lines is the same, i.e. the water movement in one direction.

As heating devices, radiators pig-iron section, the M140AO brand are used (the sizes of 582х96х140 mm, height, width, depth respectively).

Air is removed from the system through the Mayevsky crane, which is installed on each heating device of the upper floor.

Hydraulic calculation of water heating system

The calculation was performed using the characteristics method.

The basis for the calculation is the made axonometric diagram of the heating system.

The pressure loss in the individual design area is calculated as

Handle = SG2,

where S is characteristic of hydraulic resistance,

For individual unified units, given in the reference book a depending on the diameter d used;

G2 - coolant flow rate in the area, kg/h;

For multiple parcels connected in series

S = ∑Si,

where Si is the characteristic of the hydraulic resistance in the i-th section ,

The characteristic of the hydraulic resistance of the main pipeline is calculated by the formula:

S = A(l/d + ∑),

where A - specific dynamic pressure,, from reference data;

l - length of the section, m;

/ d - reduced coefficient of hydraulic friction, m-1;

∑ is the sum of local resistance coefficients on the site.

The results of the calculation are given in Appendix No. 2.

Heat engineering calculation of pipes and heating devices

The essence of the calculation is the determination of the required heating surface area of ​ ​ the separately considered heating device. The basis for the calculation is the made axonometric diagram of the heating system.

Heat input from the heating device is calculated as

Qo.p.t/post = Qpomt/post - Qtrt/post,

where Qpomt/sweat - room losses, W;

Qtrt/post - heat input from pipeline, W, by formula

Qtrt/post = qtrt,

where qtr - heat removal from 1 m of linear pipe depending on temperature difference (tg - tv) and pipeline diameter, W/m;

ltr - pipeline length, m;

tp is a correction factor that takes into account the heat fraction useful for maintaining the temperature of the internal air.

The required nominal heat flux is calculated by the formula:

where Qo.p.t/post - heat input from heating device, W;

ϕк - the complex coefficient calculated by a formula:

where tcp is the average temperature head, calculated by the formula:

tcp = tcp - tв,

tcp - average temperature i - m device, 0 С;

tv is temperature of internal air, 0 C;

n, p, c are coefficients that take into account the design features of the device;

Gpr - water flow rate in the device, kg/h;

b is a coefficient taking into account atmospheric pressure;

- coefficient that takes into account the direction of coolant movement.

tcp = tinlet - 0.5tpr,

where tinlet - coolant temperature at instrument inlet, 0 С,

tpr is fall of temperature of the heat carrier after passing of the heating device, 0 C.

where tg - design temperature of hot water in the system, 0 С;

i is the leakage coefficient of the i-th device;

Qi - thermal load of the i-th instrument, W;

to - design temperature of return water in the system, 0 С;

where с - specific heat capacity of heat carrier,;

Gpr - water flow rate in the device, kg/h;

1 is a coefficient that takes into account heat transfer through additional areas above the design;

2 is a coefficient that takes into account heat loss due to the placement of instruments near the outer walls.

Gind = Gst,

where is the flow rate;

Gst - flow rate of water in the riser, kg/h, is determined by the formula:

where Qst is the heat load of the riser, W, is calculated by the formula:

Qst = ∑Qi,

where Qi - thermal load of the i-th instrument, W;

Coolant temperature at instrument outlet is defined as

where - coolant temperature at the inlet to the i-th instrument, 0 С,

- decrease of coolant temperature after passing the heating device, 0 С.

The number of cast iron radiator sections is determined as follows:

where Qt.n. - required nominal heat flow, W;

Qn. at. - standard conditional heat flow from one section, W.

The results of the heat engineering calculation of heating devices are presented in Appendix No. 3.

Calculation of main equipment of individual local heat station

Selection of water jet elevator is performed on the basis of calculation of diameter of neck dg and diameter of nozzle dc.

dc = dr/( 1 + U) = 20/( 1 + 2.53) = 56mm = 5, 6cm

where dr - neck diameter, mm;

U is the increased displacement factor.

where Gn is the mixing rate, kg/h.

rs - pressure losses in a system, 4.324 kPa.

U=1,15U′=1,152,2=2,53,

where U ′ is the displacement factor.

Gc - coolant flow rate, kg/h.

where T1 - heat carrier temperature on an entrance to elevator knot from teploay network, 0 C;

tr - design temperature of hot water in the system;

T2 - heat carrier temperature at the exit from elevator knot in thermal network, 0 C.

where Qdd - heat loss of the entire building, W;

с - specific heat capacity of heat carrier,;

We choose elevator No. 2, since 18≤dr≤23mm.

Selection and design solutions in the natural ventilation system

The building uses a naturally induced ventilation system - this is the opening of window frames and the use of channels (air movement occurs due to pressure difference). Ventilation system refers to exhaust, by means of which contaminated air is removed from the room. As intended, it refers to general exchange (i.e. harmful substances are supplied by plenum air to the exhaust holes).

Since the number of floors in the building does not exceed 5, they are used by individual channels made of bricks. Air is removed through ventilation channels installed in the kitchen, bath, toilet. Ventilation ducts are isolated within unheated rooms. Exhaust ventilation channels are combined in the attic with a prefabricated duct, from which air is discharged to the atmosphere through the shaft. The mine is made insulated. For fire safety, the mine is wrapped with roofing steel on felt from the inside and outside. Above the shaft an umbrella is installed to prevent ingress of sediment.

Aerodynamic calculation of natural ventilation system

The purpose of aerodynamic calculation is to determine the geometric dimensions of the ventilation system.

The basis for the calculation is the completed axonometric diagram of the ventilation system.

In this residential building there is a ventilation system with a natural impulse.

rgr =ghv (N - vn),

where g - acceleration of free fall, 9.81m/s2;

hv is height from the center of a window opening of the respective floor to the mouth of the exhaust mine, sq.m;

n - air density at temperature + 5 0 С, kg/m3;

bn - indoor air density, kg/m3;

vn = 353 / (273 + tv),

tv is air temperature in the building, 0 C.

pressure losses at any branch are the total pressure losses at the design areas:

rusty = ∑pi,

where pi is the pressure loss in the i-th section calculated by the formula:

pi = Rilii + zi,

where Ri - specific pressure losses occurring at 1 m of the length of the section, Pa/m, are taken according to a nomogram depending on the air speed and section of the section.

li - length of the section, m;

i is the roughness coefficient of the section material.

zi - pressure loss on local resistances, Pa.

The equivalent duct diameter is as follows:

deq = 2ab/( a + b),

where a, b are the geometric dimensions of the channel, m.

where ∑ is the sum of local resistance coefficients;

c - air density in the area, kg/m3;

V - air velocity in the area, m/s.

The results of the calculation are presented in Annex No. 4.

Literature used

1. SNiP II3 79 * * "Construction heat engineering."

2. SNiP 2.01.0182 "Construction climatology and geophysics."

3. SNiP 2.08.0189 "Residential buildings."

4. Theological V.N. "Heating and Ventilation" - Stroyizdat, 1980

5. Skanavi A.N. "Heating" - Moscow, 1988

Designer Reference Book. Staroverov I.G. Ch.1. "Heating, water supply, sewerage" - Stroyizdat, 1975.

11. Equipment Explication.