title: Ensuring cost-effective heat exchanger network design for non-continuous processes

authors: Morrison, Andrew S.

subjects: Capital costs

abstract: The variation in stream conditions over time inevitably adds significant complexity to the task of integrating non-continuous processes. The Time Averaging Method (TAM), where stream conditions are simply averaged across the entire time cycle, leads to unrealistic energy targets for direct heat recovery and consequently to Heat Exchanger Network (HEN) designs that are in fact suboptimal. This realisation led to the development of the Time Slice Method (TSM) that instead considers each time interval separately, and can be used to reach accurate targets and to design the appropriate HEN to maximise heat recovery. However, in practise the HENs often require excessive exchanger surface area, which renders them unfeasible when capital costs are taken in to account. An extension of the TSM that reduces the required overall exchanger surface area and systematically distributes it across the stream matches is proposed. The methodology is summarised with the help of a simple case study and further improvement opportunities are discussed

text: Ensuring cost-effective heat exchanger network design for non-continuous processes The variation in stream conditions over time inevitably adds significant complexity to the task of integrating non-continuous processes. The Time Averaging Method (TAM), where stream conditions are simply averaged across the entire time cycle, leads to unrealistic energy targets for direct heat recovery and consequently to Heat Exchanger Network (HEN) designs that are in fact suboptimal. This realisation led to the development of the Time Slice Method (TSM) that instead considers each time interval separately, and can be used to reach accurate targets and to design the appropriate HEN to maximise heat recovery. However, in practise the HENs often require excessive exchanger surface area, which renders them unfeasible when capital costs are taken in to account. An extension of the TSM that reduces the required overall exchanger surface area and systematically distributes it across the stream matches is proposed. The methodology is summarised with the help of a simple case study and further improvement opportunities are discussed

year: 2012

title: Effect of flow distribution on the photovoltaic performance of a building integrated photovoltaic/thermal (BIPV/T) collector

authors: Ghani, Faisal Abid

subjects: building integrated

abstract: The phenomenon of non-uniform flow distribution and its influence on thermal performance within a traditional solar thermal collector is well known. Its effect on the photovoltaic conversion of a hybrid photovoltaic/thermal (PV/T) collector however has received little attention. In this study an investigation has been carried out to determine what effect flow distribution will have on the photovoltaic yield of a BIPV/T collector of various size. A three step numerical analysis was conducted to model flow distribution, temperature variation, and photovoltaic yield for a PV/T collector of various design (manifold sizes), geometric shape (aspect ratio), and operating characteristics (mass flow rate and flow direction in manifolds) in order to vary flow uniformity within the collector. The results revealed that flow distribution within the collector will have a significant influence on the photovoltaic performance of a hybrid PV/T collector. For the scenario where flow distribution was most uniform, photovoltaic performance was improved by over 9% in comparison to a traditional photovoltaic (PV) collector operating under the same conditions. For poor flow however, performance was only improved by approximately 2%. Parameters found to influence flow distribution include the manifold to riser pipe ratio where a ratio of 4:1 was found to be ideal and that increasing to a 6:1 ratio offered negligible improvement. Additionally it was found that array geometry (characterised by its aspect ratio in this study) plays an important role on both flow distribution and photovoltaic yield. This study has identified that the optimal mass flow rate is dependent on the shape or aspect ratio of the array.

text: Effect of flow distribution on the photovoltaic performance of a building integrated photovoltaic/thermal (BIPV/T) collector The phenomenon of non-uniform flow distribution and its influence on thermal performance within a traditional solar thermal collector is well known. Its effect on the photovoltaic conversion of a hybrid photovoltaic/thermal (PV/T) collector however has received little attention. In this study an investigation has been carried out to determine what effect flow distribution will have on the photovoltaic yield of a BIPV/T collector of various size. A three step numerical analysis was conducted to model flow distribution, temperature variation, and photovoltaic yield for a PV/T collector of various design (manifold sizes), geometric shape (aspect ratio), and operating characteristics (mass flow rate and flow direction in manifolds) in order to vary flow uniformity within the collector. The results revealed that flow distribution within the collector will have a significant influence on the photovoltaic performance of a hybrid PV/T collector. For the scenario where flow distribution was most uniform, photovoltaic performance was improved by over 9% in comparison to a traditional photovoltaic (PV) collector operating under the same conditions. For poor flow however, performance was only improved by approximately 2%. Parameters found to influence flow distribution include the manifold to riser pipe ratio where a ratio of 4:1 was found to be ideal and that increasing to a 6:1 ratio offered negligible improvement. Additionally it was found that array geometry (characterised by its aspect ratio in this study) plays an important role on both flow distribution and photovoltaic yield. This study has identified that the optimal mass flow rate is dependent on the shape or aspect ratio of the array.

year: 2012

title: E tama Hikairo

authors: Maxwell, Te Kahautu

subjects: Oriori

abstract: He oriori tēnei mō Hikairo, te mokopuna tuatahi a Kīngi Tūheitia. He oriori tēnei e whakanui ana i a Hikairo, tōna whakapapa, tōna tūranga i te ao Māori me te ao Kīngitanga. He mokopuna Ringatū anō a Hikairo, nā Kīngi Tūheitia i tuku mai a Hikairo kia tūātia e Te Hāhi Ringatū ki te Poukai o Wāhi Pā i te tuawaru o Whiringa-ā-Nuku 2014. Ka whakaaturia tōna whakapono Hāhi Ringatū ki roto i te oriori nei e kupu whakaaritia ana. I tohua hoki e Kīngi Tūheitia a Te Kāhautu hai pou whakaruruhau1 mō Hikairo koinei ia i titoa ai tēnei oriori mō tana tamaiti mokopuna, mō Hikairo. He aroha nui nō te matua mō wai oti, mō Hikairo.

I titoa tēnei oriori hai waiatatanga mā te kapa haka o Ōpōtiki Mai Tawhiti. I waiatatia e Ōpōtiki Mai Tawhiti tēnei ki Te Matatini i tū ki Ōtautahi te tau rua mano tekau mā rima. He huarahi anō tēnei mā Te Kāhautu ki te whakamānawa i tana mokopuna i a Hikairo, nara nā te kapa haka a Te Kāhautu i waiata, i whakanui a Hikairo ki te maraenui o te iwi Māori, ko Te Matatini. Ana i tuatahi a Hikairo i te wehenga o Te Waiata Tira. “E Tama Hikairo, haere mai rā.”

text: E tama Hikairo He oriori tēnei mō Hikairo, te mokopuna tuatahi a Kīngi Tūheitia. He oriori tēnei e whakanui ana i a Hikairo, tōna whakapapa, tōna tūranga i te ao Māori me te ao Kīngitanga. He mokopuna Ringatū anō a Hikairo, nā Kīngi Tūheitia i tuku mai a Hikairo kia tūātia e Te Hāhi Ringatū ki te Poukai o Wāhi Pā i te tuawaru o Whiringa-ā-Nuku 2014. Ka whakaaturia tōna whakapono Hāhi Ringatū ki roto i te oriori nei e kupu whakaaritia ana. I tohua hoki e Kīngi Tūheitia a Te Kāhautu hai pou whakaruruhau1 mō Hikairo koinei ia i titoa ai tēnei oriori mō tana tamaiti mokopuna, mō Hikairo. He aroha nui nō te matua mō wai oti, mō Hikairo.

I titoa tēnei oriori hai waiatatanga mā te kapa haka o Ōpōtiki Mai Tawhiti. I waiatatia e Ōpōtiki Mai Tawhiti tēnei ki Te Matatini i tū ki Ōtautahi te tau rua mano tekau mā rima. He huarahi anō tēnei mā Te Kāhautu ki te whakamānawa i tana mokopuna i a Hikairo, nara nā te kapa haka a Te Kāhautu i waiata, i whakanui a Hikairo ki te maraenui o te iwi Māori, ko Te Matatini. Ana i tuatahi a Hikairo i te wehenga o Te Waiata Tira. “E Tama Hikairo, haere mai rā.”

year: 2016