THE THEORETICAL ANALYSIS OF INFLUENCING OPERATIONAL FACTORS ON WORKING ABILITY OF THE TIGHT UNITS OF HOUSEHOLD REFRIGERATING APPLIANCES Текст научной статьи по специальности «Физика»

ISSN 2223-4047

BecmnuK Maeucmpamypu. 2016. № 5(56). T. II

UDC 621.569.92.041

A.S. Korotkov, E. V. Rogalskaya

THE THEORETICAL ANALYSIS OF INFLUENCING OPERATIONAL FACTORS ON WORKING ABILITY OF THE TIGHT UNITS OF HOUSEHOLD REFRIGERATING APPLIANCES

In this paper the analysis of operational factors which determines the peculiarities of theoretical cycle sealed unit and the power operating in the efficiency of operation of compression household refrigerating appliance.

Keywords: Domestic refrigeration unit, performance, Theo-theoretical cycle, sealed unit.

The Household Refrigerating Appliance (HRA) are machines, working without special care of the consumer during the whole term of a possible operating time [1].

Operating features of household refrigerating appliances in comparison with other classes of refrigerators are the most severe conditions to their usage for a destination [2].

The tight system of the refrigerating unit doesn't provide access to operating process of built-in electric motor of cooling compressor; air temperature of the condenser and a casing of cooling compressor the air temperature during the summer period can reach 50 °C and more; so in the process of using HRA irreversible physical and chemical processes and reactions between components of a working environment and materials of subsystems of the HRA tight unit, may take place [2]. ]. Modern operating experience of BHP shows that generally changing in their technical condition is caused by influence of the following operational factors:

- operating mode of the BHP tight unit;

- temperature and speed of the air movement of air around the condenser and the cooling compressor;

- wear of interfaces of the cooling compressor;

- contaminating internal system of the BHP tight unit;

- quantity and presence of the refrigerating agent;

- door density of BHP ;

- the degree of product loading. [3].-

All above-mentioned factors, as a rule, reduces BHP refrigerating capacity thus ensuring the demanded standard temperature level in low-temperature and refrigerating offices, the corresponding devices of automatic equipment of managing BHP increase the value of coefficient of working hours of cooling compressor, reduce refrigerating coefficient of the refrigerator and its work resource.

From the point of view of the analysis of thermodynamic cycles it causes changing thermal characteristics of locating points of a cycle and increasing costs of operation of the refrigerator

Existing additional resistance as a result of a contaminating internal system of the tight unit on the way a Freon movement the emergence of process 6r-6o are appeared, (fig. 1) characterizing pressure decrease in a path on the ways to the evaporator and as a result the process of evaporation with lower pressure 6ro-1o..can occur

2 p

Fig. 1. The scheme of a thermodynamic cycle of 1-1р-2р-Зр-4р-5р-6р a regenerative cycle with adiabatic compression-the valid cycle of the tight unit of the household refrigerator1о-1ро-2ро-Зро-4ро-5р-6ро in the presence of operational deposits in a liquid path-

T

S

g

© Korotkov A.S., Rogalskaya E.V., 2016.

BecmnuK Maeucmpamypu. 2016. № 5(56). T. II

ISSN 2223-4047

Thus the heating of steam, prior to compression is carried out on an isobar 1o-1po. Thus, the area 1o-1po-1p-1-6p-6po represents the additional expense of work in a cycle caused by imperfection of the existing means of cleaning a working environment in the presence of objective factors of destabilization of constructive and functional elements

Decreasing in specific mass refrigerating capacity assumes increase in specific volume of steam which is soaked up that leads to increase a compression in specific work on the one hand and to pressure decrease of condensation from another. As a result of the valid thermodynamic cyclecharacteristic taking into account possible change of coordinates the located points of the line of a high pressure. Due to operational characteristics of household refrigerators characterized by small expenses as shown in the analysis of references, the decline in production caused by existence in operational deposits will lead to process mixture of condensation in T coordinates - S as the provision of the proceedingprocess on an isobar 4ro-Zro-2ro. 2ro-2r-Zr-4r-4roSquarecharacterizespossiblereductionofworkofacycle

(T - T )(S3 - S3)

3 n 3 n/i 3 nn 3n

F

2

the mnogrannike -3po-2po-2p-3p will make the area: the area of it will be:

lr s2 (7 + 7 ) - S3 (7 - 7 + 7 - 7 ) - S3 (t 3 -7 )

F

2

-the area of a quadranglee -3p-4p-4po will be:

F

(S3 - S4 ) + (S3 - S4 )

3P 4po P 4P

2

(73. - Ta)

(5)

(6)

(7)

where S4p and S4po - according to entropy of a cycle with adiabatic compression and the real unit in the presence of deposits;

T4po - temperature of saturated liquid for the real unit with deposits.

In general, decrease in work of a cycle equivalent to the area 3po-2po-2p-3p-4p-4powill be:

iKg _ 1 _ 2

S2 (72 + T3 ) - S2 (7 + T3 ) - S3 (T 3 -T2 ) -

2 P 2P 3P 2po 2 po 3P 3pо 3p 2pо

-S3 (2T4 - T3 + T2 - 2T3 ) - (73 - T4 )(Sa + S4 )

3nn ~ n/i 3 n 2n 3 n/i 3 n ~ n/i ~ n/i ~n

(8)

where the "cd" index" means the reduction of work by lines of a high pressure caused by decline in production.

Growth of specific work of a cycle on the party of low pressure is defined by algebraic addition of the: a-1-1p-c, a-1-1o-6, 6-1o-1po-cng-1-6p-6po.

F1o -Ipo -1p-6p-6o _ ^a-l-lp-c - (Fa-1-1o-6 + F6-10 -1po -c ) + Ffl-1-10 + Ffl-1-6p-6po

The area 1-1o-1po-1pis determined:

— — —

Si (71 + Ti) - Si(T, - 71 ) - S, (T1 -71 ) - S,(T, + 71 )

Theare 1o-1po-1p-1-6p-6po, other components are defined from the following expressions: - area of a triangle g-1-10:

(T - r.xs, - S1)

F

g-i -io

2

(9)

(10)

where - Si and Si0 - entropy respecting to a regenerative cycle adiabatic compression and the real unit on the line of saturation:

Ti and Tio - temperatures corresponding to them.

In the aread-10-1p0-1p-1 are:

F

a-1o-1po -1p-1

2

S1p (Tp + T1 ) - S1 (71 p - + T1 - T1o ) - (T 1 -Tpo ) - ^Ipo (Tpo + T1o )

Area of a quadrangle g -1-6p-60:

1

ISSN 2223-4047

Вестник Maeucmpamypu. 2016. № 5(56). T. II

(S - )(S1-S6p )(T - t )

g-1-60 -6po - 2 ' (12)

where S6p and S6po — according to entropy of points of the termination of a drosselirovaniye for cycles regenerative initial and in the presence of deposits; T6po- temperature equal Tlo

As a result growth of working cycle of the lower bound caused by decrease is defined by the equation:

1 S, (T, + T) - S, (T, + T, ) - S, (T, -T, ) --S, (2T6 - T + T, - 2T, ) - (T, - T6 )(S, + S, ) (13)

1BC _

«o - 2

The areas the characterizing work costs of realizing corresponding processes can be determined by integration of the equations of the lines characterizing each concrete process of the considered cycle.

Foranexample 1-1o-1po-1p characterizing growth of work of a cycle caused by existence of deposits in the course of heating of steam prior to compression can be defined by expression:

1 J* (S-S1)(T1P -Ti)+T1 (Sip -S_) Vs - SiXT, - T)+Ti(Sq - Si)

1-1<> -1PO-1P J c c J e _ e

S; Sip -Si S Si„ Si

S (14)

Sipo (S - Si)(T - T)+T (Si - Si)

I ^ ' v ^ 1 ' 1 ^ 1 po_^

„ s_ s_ S10 _po _O

Similarly other components of working cycle are defined and their quantitative characteristicssre decided with the help of subsequent computer processing.

Generally, the equation for defining the work of a real cycle Takingintoaccountexistenceofdepositsinageneralviewcanbepresentedintheform:

l = l -lKd + lec, (15)

po p ^o v '

where 1 - - the work made in a regenerative cycle of the household compression of a refrigerator to a cycle with adiabatic compression of superheated steam and regeneration

l^o H C - respectively a size of the private works caused by existence of deposits and leading to change of characteristics of the applied thermodynamic cycle.

As shown by L.M. Rosenfeld the size l within temperature borders, characteristic for real service conditions of household compression refrigerators, can be presented in the form

T-T

ip- • Cx (t-T; )

„ M HM T K------+ H

c 2T 1 ^

2 ßi-1 T-To 1 T-To A-1

■ +1

J

(16)

where: T and To - according to value of temperatures, characteristic for the upper and lower bound of a regenerative cycle;

C'x - thermal capacity of liquid R134a( Freon ) on the left boundary curve in the chart; K - the dimensionless criterion characterizing thermodynamic properties of R134a freon within temperature borders of the applied cycles size K is defined from a formula:

r

K — o

C'x [T-T0 ]'

where ro - warmth of steam formation of liquid R134a freon;

The m - the dimensionless criterion characterizing temperature borders of a cycle size M is defined from expression

T

M =

T

M

where TM - arithmetic average value of temperatures characteristic for the top and lower borders,

-„ + -

T„ —

o

Вестник магистратуры. 2016. № 5(56). Т. II

ISSN 2223-4047

the size L characterizes the relation of thermal capacities of superheated steam and saturated liquid within temperature borders of a cycle is defined from expression

CX X = — Cx'

where Cx'' - thermal capacity of superheated steam, with a constant pressure.

jUx - coefficient of transformation of a cycle of the thermal pump

L1 - the dimensionless complex characterizing a ratio of thermal capacities of superheated steam and saturated liquid the size LI is defined from expression X =-

Cx'

Takenintoaccount / may be written:

j Cx '

p = E

T - T )

2 M-1 ' T -T

+Л,

2T

(T3p -T )(* -1)

+1

(17)

whereEc -refrigerating coefficient of an ideal cycle of Carno. The size of specific mass refrigerating capacity is defined from Equations;

= r

'o

EP° =

T3p (AGa2 )k-T1 (g )*

real thermodynamic cycle 1c

T3r (ÂGa2)-Т (ÂGa )k

0

As a result refrigerating coefficient of a real thermodynamic cycle 1c-1pc-2pc-3pc-4pc-5p-6pcwill be:

\k /-\k

(Cx '+ Cp )

-2 -З -4 -

э -^ро ч-'ро ^ро

(Cx '+ Cp )

(18)

1

(19)

p°

Thus, having parameters of changing an expense of the refrigerating agent AGa AGa2 caused by influence of operational factors with use of the equations (1) and (2) it is possible to define theoretical change of work of the applied cycle in comparison with a basic, and then known way to define extent of decrease in power efficiency of a real cycle and respectively a working ability of the household refrigerating appliance.

References:

1. Jacobson W. B. Small refrigerators. - M.: Food industry, 1977. - 368 pages.

2. Kozhemyachenko A.V. Determining maximum permissible values of power indicators of quality of household compression refrigerating appliances / A.V. Kozhemyachenko, S. P. Petrosov, M. A. Lemeshko, etc.News higher education-al..-C. Region.Technical science, 2014. - page 132-138.

3. Kozhemyachenko A.V. Influence of pollution on operability of tight units of household refrigerators and increase of their power operational characteristics at repair: yew. ...Cand.Tech.Sci.: defended 15.02.88: adopted. 08.06.88. - M.: MTI. - 201 pages.

4. Rosenfeld L.M. Refrigerators and units / L.M. Rosenfeld, A.G. Tkachyov. - M.:gostorizdat, 1962. S-656.

5. Osokin V. V. About influence of ambient temperature on heat power characteristics of the household refrigerator. / V. V. Osokin, A.B. Kudrin, M. V. Dyomin // Holodilna of a tekhn_k of iTexHomria. Odessa, 2011. No. 1(129). Page 17-22.

6. Modern systems of ventilation and air conditioning: [Studies. grant] / G. V. Nimich, V.A. Mikhaylov, E.S. Bondar. - To.: TOV "Vidavnichybudinok "the Outpost - Primas" 2003. - 630 pages.

7. Badylkes I.S. Working substances and processes of refrigerating cars / I.S. Badylkes. - M.: Gostorizdat, 1962.-280

pages.

°

КОРОТКОВ АЛЕКСЕЙ СЕРГЕЕВИЧ - магистрант направления технологические машины и оборудование, Институт сферы обслуживания и предпринимательства (филиал) ДГТУ в г. Шахты, Россия.

РОГАЛЬСКАЯ ЕКАТЕРИНА ВЛАДИМИРОВНА - магистрант направления технологические машины и оборудование, Институт сферы обслуживания и предпринимательства (филиал) ДГТУ в г. Шахты, Россия.