title: Impact of hybrid heat transfer enhancement techniques in shell and tube heat exchanger design

authors: Shekarian, Ehsan

abstract: Despite the advantages of shell and tube heat exchangers, one of their major problems is low thermal efficiency. This problem can be improved by using heat transfer enhancement techniques such as adding nanoparticles to the hot or cold fluids, and/or using tube inserts as turbulators on tube side as well as changing baffles to a helical or twisted profile on the shell side. Although all of these techniques increase the thermal efficiency; however, engineers still need a quantitative approach to assess the impact of these technologies on the shell and tube heat exchangers. This study attempts to provide a combination of such techniques to increase the impact of these improvements quantitatively. For this purpose, at first stage the thermal and hydraulic characteristics of pure fluid, Al₂O₃/water nanofluid in a plain tube equipped with and without twisted tape turbulator is evaluated based on a developed rapid design algorithm. Therefore, the impact of using enhanced techniques either in form of individual or in hybrid format and the increase of nanoparticle concentration in base fluid have been studied. The results show that using turbulators individually and in hybrid format with nanofluid can be effected on design parameters of a typical heat exchanger by reducing the required heat transfer area up to 10 %.

text: Impact of hybrid heat transfer enhancement techniques in shell and tube heat exchanger design Despite the advantages of shell and tube heat exchangers, one of their major problems is low thermal efficiency. This problem can be improved by using heat transfer enhancement techniques such as adding nanoparticles to the hot or cold fluids, and/or using tube inserts as turbulators on tube side as well as changing baffles to a helical or twisted profile on the shell side. Although all of these techniques increase the thermal efficiency; however, engineers still need a quantitative approach to assess the impact of these technologies on the shell and tube heat exchangers. This study attempts to provide a combination of such techniques to increase the impact of these improvements quantitatively. For this purpose, at first stage the thermal and hydraulic characteristics of pure fluid, Al₂O₃/water nanofluid in a plain tube equipped with and without twisted tape turbulator is evaluated based on a developed rapid design algorithm. Therefore, the impact of using enhanced techniques either in form of individual or in hybrid format and the increase of nanoparticle concentration in base fluid have been studied. The results show that using turbulators individually and in hybrid format with nanofluid can be effected on design parameters of a typical heat exchanger by reducing the required heat transfer area up to 10 %.

year: 2016

title: The relationship between the 'push' and 'pull' factors of a tourist destination: the role of nationality - an analytical qualitative research approach

authors: Prayag, Girish

subjects: push factors

abstract: Using qualitative research techniques, this paper explores the relationship between the 'push' and 'pull' factors of a destination and the influence of nationality on these factors. These relationships were explored for a sample of 103 international tourists to Mauritius. The data were analysed by using (a) thematic analysis and (b) an analysis using the text analysis programme, CatPac. The results indicated relationships between specific motives, cognitive and affective images and it was also found that nationality has a strong influence on these variables. Different motives for visiting Mauritius were found to exist between different national groupings. Implications for use of thematic and content analysis, management of destination, marketing and tourist experiences are provided.

text: The relationship between the 'push' and 'pull' factors of a tourist destination: the role of nationality - an analytical qualitative research approach Using qualitative research techniques, this paper explores the relationship between the 'push' and 'pull' factors of a destination and the influence of nationality on these factors. These relationships were explored for a sample of 103 international tourists to Mauritius. The data were analysed by using (a) thematic analysis and (b) an analysis using the text analysis programme, CatPac. The results indicated relationships between specific motives, cognitive and affective images and it was also found that nationality has a strong influence on these variables. Different motives for visiting Mauritius were found to exist between different national groupings. Implications for use of thematic and content analysis, management of destination, marketing and tourist experiences are provided.

year: 2011

title: Te kiri ka tōkia e te anu: Ko ētahi āhuatanga ki ngā kāinga o Hiruhārama me Te Horo

authors: Parata, Patricia Hekia

subjects: Tangihanga

abstract: He mea waihanga e ahau, tēnei tuhituhinga, i runga i tēnei whakaaro, kia tirohia te hanga, me te āhua o te tangihanga, ki ōku marae e rua, o roto o Ngāti Porou, kei Hiruhārama me Te Horo. Kāore i whāia he wāhanga ki ngā pūtakenga mai o ngā tikanga. Engari, he mea tātaki haere noa iho ko ngā kaupapa tauira o ēnei tikanga. 
He mea raranga anō ngā kōrero nei, kia whiri ai i roto i ngā tauira kōrero nei, te tūpāpaku, te marae, ngā tāngata me ngā tikanga, e pā ana ki a rātau katoa. 
Ahakoa te nui, te huhua noa iho, o ngā tuhituhinga mō te āhua ki tēnei mea, ki te marae, te whaikōrero, te tangihanga, ēnei mea katoa, kore rawa anō nei, tētahi paku tuhituhi kua whakatakotoria i tēnei hanga nei. Ehara hoki tēnei i te tuhituhinga e whai ana i te āhua o ērā o mua atu. 
He mea kohikohi ēnei kōrero, nā ētahi kuia, me ētahi kaumātua, me ngā mea pakeke o tōku nei rohe, ā, he aronga nui nāku ki ngā mea i kite ai au i ngā wā i ahau i te kāinga, me ngā hui i tae ai au mai anō i tōku tamarikitanga. Nō reira, he whakapūteatanga ēnei mea katoa, nō ngā mea katoa i runga ake nei. 
Kua wehewehengia ēnei kōrero kia takoto pēnei ana nā: ko te wāhanga tuatahi, ko te takenga mai o Ngāti Porou, me ngā wehewehenga mai o ngā hapū; ko te wāhanga tuarua, e pā ana ki ngā whakamārama o ngā kupu, arā, te kirimate, te paemate, me te wharemate; tuatoru, ko te whakahoki o te tūpāpaku; tuawhā, kei ngā mahi ki runga i te marae; tuarima, ngā tikanga o te rā nehu; tuaono, ngā mahi whakatutuki. 
Hei whakamutu ake, kua whakarārangitia e ahau, ngā roherohenga mahi, me ngā tūranga e rite ana mō tēnā, mō tēnā, mō tēnā.

text: Te kiri ka tōkia e te anu: Ko ētahi āhuatanga ki ngā kāinga o Hiruhārama me Te Horo He mea waihanga e ahau, tēnei tuhituhinga, i runga i tēnei whakaaro, kia tirohia te hanga, me te āhua o te tangihanga, ki ōku marae e rua, o roto o Ngāti Porou, kei Hiruhārama me Te Horo. Kāore i whāia he wāhanga ki ngā pūtakenga mai o ngā tikanga. Engari, he mea tātaki haere noa iho ko ngā kaupapa tauira o ēnei tikanga. 
He mea raranga anō ngā kōrero nei, kia whiri ai i roto i ngā tauira kōrero nei, te tūpāpaku, te marae, ngā tāngata me ngā tikanga, e pā ana ki a rātau katoa. 
Ahakoa te nui, te huhua noa iho, o ngā tuhituhinga mō te āhua ki tēnei mea, ki te marae, te whaikōrero, te tangihanga, ēnei mea katoa, kore rawa anō nei, tētahi paku tuhituhi kua whakatakotoria i tēnei hanga nei. Ehara hoki tēnei i te tuhituhinga e whai ana i te āhua o ērā o mua atu. 
He mea kohikohi ēnei kōrero, nā ētahi kuia, me ētahi kaumātua, me ngā mea pakeke o tōku nei rohe, ā, he aronga nui nāku ki ngā mea i kite ai au i ngā wā i ahau i te kāinga, me ngā hui i tae ai au mai anō i tōku tamarikitanga. Nō reira, he whakapūteatanga ēnei mea katoa, nō ngā mea katoa i runga ake nei. 
Kua wehewehengia ēnei kōrero kia takoto pēnei ana nā: ko te wāhanga tuatahi, ko te takenga mai o Ngāti Porou, me ngā wehewehenga mai o ngā hapū; ko te wāhanga tuarua, e pā ana ki ngā whakamārama o ngā kupu, arā, te kirimate, te paemate, me te wharemate; tuatoru, ko te whakahoki o te tūpāpaku; tuawhā, kei ngā mahi ki runga i te marae; tuarima, ngā tikanga o te rā nehu; tuaono, ngā mahi whakatutuki. 
Hei whakamutu ake, kua whakarārangitia e ahau, ngā roherohenga mahi, me ngā tūranga e rite ana mō tēnā, mō tēnā, mō tēnā.

year: 1983