Vertical Distribution of Air Temperatures in Heated Dwelling Rooms

Ve ical Dis ibu ion o Ai Tempe a u es in Hea ed Dwelling Rooms Ond ej Sikula Uni e si y o Technology B no, B no Co esponding email: [email p o ec ed] SUMMARY The pape p esen s an expe imen al and heo e ic esea ch on one o ac o s in luencing he indoo clima e in dwelling ooms hea ed by hea ing sys ems – he e ical dis ibu ion o empe a u es. The pape summa izes esul s om simula ion o he oom hea ed by a gas space hea e and a pla e adia o . Among main ac o s causing un a o able dis ibu ion o empe a u es in a oom belong insu icien elimina ion o cold d opping ai lows and high empe a u e o hea ing ai . INTRODUCTION The subjec o he pape belongs o he ield o o ma ion o indoo clima e in esiden ial buildings. One o ac o s in luencing he quali y o indoo clima e in a dwelling oom is he e ical dis ibu ion o empe a u es. I is desc ibed by a e ical empe a u e g adien o by empe a u e di e ence be ween he posi ion o a head and an ankle o a pe son in he gi en space. Indoo clima e is c ea ed by a ious HVAC sys ems which ha e di e en in luences on he obse ed e ical dis ibu ion o empe a u es. We y o iden i y ac o s leading o un a o able e ical dis ibu ion o empe a u es in a oom hea ed by a gas space hea e and a pla e adia o . METHODS The e ical dis ibu ion o empe a u es o chosen spaces was in es iga ed by expe imen al measu emen s and CFD simula ions. The measu emen was pe o med du ing a egula ope a ion o chosen ooms. The oom A is a dwelling oom in an old b ick house wi h one ou e wall. The oom is si ua ed in he hi d loo unde a cold sloping oo wi h leaking iling. Su ounding spaces ha e he same o simila empe a u e egime. The walls a e made o solid b icks; he ceiling is made o wooden gi de s. The leaking wooden windows and balcony doo s in he oom ha e a double glassing. The oom is hea ed by a local gas space hea e , see ig. 1a). The oom B is an o ice o wo people in a new building wi h one ou e wall made o medium hick açade, see ig. 1b). The o ice is su ounded by ooms wi h he same o simila empe a u e egime. P oceedings o Clima 2007 WellBeing Indoo s a) b) Figu e 1. Geome y o ooms In case A was measu ed and in es iga ed he e ical dis ibu ion o empe a u es while p e- hea ing. In case B was measu ed and in es iga ed he e ical dis ibu ion o empe a u es while sho - e m en ila ion by windows. CFD simula ions we e pe o med on simpli ied geome ic models o eal ooms. Simula ions included s a iona y and non-s a iona y solu ion o he mal ans e by con ec ion, conduc ion and adia ion. Fo ai low u bulence calcula ions he RNG k-ε model wi h s anda d wall unc ions was used. The hea ans e was sol ed by DO (Disc e e o dina es) model [3]. Bounda y condi ions o CFD simula ions we e aken om he expe imen al measu emen . The expe imen al measu emen consis s o measu emen o ai empe a u e and ai low eloci y. We pe o med he measu emen o he ai empe a u e, he loo empe a u e, he ceiling empe a u e and he ou e ai empe a u e. We also compa ed he mal ields by using he mo-g aphical images showing su ace empe a u es o in e nal cons uc ions in he oom. Ai low eloci ies we e measu ed by anemome e s. This pape p esen s only esul s om empe a u e measu emen s. F om he poin o iew o he mal com o is ecommended he maximal empe a u e di e ence be ween he posi ion o a head and an ankle o be 2,0 K o s anding pe son and 1,5 K o si ing pe son, see [2]. The legal egula ion o wo king en i onmen equi es he maximal e ical empe a u e di e ence o be 3 K, see [1]. RESULTS A ig. 2, 4 we can see he cou se o measu ed empe a u es in chosen ime in e als. Ai empe a u es a e ma ked by a blue colo and loo and ceiling empe a u es by a ed colo . Ve ical dashed lines indica e ime momen s in which we e obse ed e ical dis ibu ions o empe a u es in he oom. In case A we can also see empe a u e o he ai coming ou o he gas space hea e ma ked by black colo a ig. 2. P oceedings o Clima 2007 WellBeing Indoo s Figu e 2. Tempe a u e cou se in ime, case A Figu e 3. Ve ical dis ibu ion o empe a u es, case A P oceedings o Clima 2007 WellBeing Indoo s case B Figu e 4. Tempe a u e cou se in ime, case B Figu e 5. Ve ical dis ibu ion o empe a u es, case B Ob ained esul s show un a o able e ical dis ibu ion o empe a u es in he oom o case A especially by p e-hea ing, see ig. 2. Inhabi an s o his oom a e exposed o he mal discom o because o he se iously o e eached maximal empe a u e di e ence be ween he posi ion o a head and an ankle equi ed by [1] o ime in e al o app oxima ely 30 minu es, P oceedings o Clima 2007 WellBeing Indoo s see ig. 3. The gas space hea e used in he oom is equipped wi h jump egula ion swi ch on- o . The e is no possibili y o s ep-by-s ep egula ion o g adual con ol o hea ing, he e o e he discom o occu s se e al imes pe day, see ig. 9. Case B o e s a o able e ical dis ibu ion o empe a u es in he oom du ing a egula ope a ion. While sho - e m en ila ion by windows is o med a cold ai laye close o he loo which cause a sligh he mal discom o el by inhabi an s. Ne e heless he maximal empe a u e di e ence be ween he posi ion o a head and an ankle equi ed by [1] is no o e eached. E alua ion o his subjec i e he mal discom o will be pe o med in he u u e. Sec ion A1 Sec ion A2 Figu e 6. Veloci ies, case A Sec ion B1 Sec ion B2 Figu e 7. Veloci ies, case B P oceedings o Clima 2007 WellBeing Indoo s Figu e 8. Pa h lines, case B P oceedings o Clima 2007 WellBeing Indoo s Figu e 9. Tempe a u e in he cou se o day, case A Figu e 10. Su ace empe a u es, case A DISCUSSION Abo e men ioned and desc ibed esul s p o e dependence o e ical dis ibu ion o empe a u es in he hea ed oom on ime. In some dynamic s a es i can be conside ed as P oceedings o Clima 2007 WellBeing Indoo s un a o able, o example while p e-hea ing in case A, o while sho - ime en ila ion by windows in case B. Following ac o s ha ing un a o able in luence on e ical dis ibu ion o empe a u es we e ound: - en ila ion by windows o high in il a ion o he ou e ai - he o ma ion o d opping ai lows a he icini y o cool su aces o ou e walls and windows - ela i ely high empe a u e o he hea ing ai O he ac o causing un a o able e ical dis ibu ion o empe a u es is an insu icien shading ou o d opping cool ai lows by a hea ing ai , see ig. 6, 7, 8. The eason o a ela i ely high empe a u e o a hea ing ai in case A is abo e all he an unsui able con ol sys em o a gas con ec o , see ig. 9. ACKNOWLEDGEMENT The pape was w i en wi h he suppo o he p og am TRVALÁ PROSPERITA na ional esea ch p og am II., MPOČR code 2A – 1TP1/119. Nume ical calcula ion in he Fluen so wa e was pe o med in conjunc ion wi h he company Sob ie y L d. REFERENCES 1. Regula ion No. 523/2002 Col. 2. FLUENT Use 's Guide, Feb ua y 2003. 3. Cihelka, J. Vy ápění a ě ání, P aha: SNTL, 1969. 610 p. P oceedings o Clima 2007 WellBeing Indoo s