Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube
Autor(a) principal: | |
---|---|
Data de Publicação: | 2020 |
Tipo de documento: | Dissertação |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFMG |
Texto Completo: | http://hdl.handle.net/1843/35980 https://orcid.org/0000-0001-5449-3582 |
Resumo: | Heat pumps are equipment used to promote space heating, to supply hot water or used for other heating purposes. The number of these systems should raise 16 times by 2050, as a contribution to meet the Paris agreement objectives. Despite presenting a relatively high efficiency, e.g. compared to electric resistance heaters, heat pumps still need to be developed. Direct-expansion solar-assisted heat pumps (DX-SAHP) are one alternative to improve the performance of air source heat pumps (ASHP). In this work, the behavior of a CO2 DX-SAHP is investigated under different operational conditions. However, the adjustable area expansion device (e.g. electronic expansion valve – EEV), generally used, was replaced by a capillary tube as an alternative to reduce the manufacturing costs. Initially, an algebraic solution to design an adiabatic coiled capillary tube operating in transcritical CO2 cycle was developed. Three different friction factors and three different k factors, related to the specific volume, were analyzed, creating a total of 9 possible combinations. After designing and assembling the tubes onto the workbench, tests were performed following a factorial design, with 2 different capillary tubes and 3 different operating conditions, namely: high solar radiation (HSR), low solar radiation (LSR), and low solar radiation with fan (LSR+fan). The results indicated an average augment of 57.9% on the heating capacity, 42.3% on COP, and 35% on the refrigerant mass flow rate, when changing from LSR (6 W/m²) to HSR (969 W/m²). The superheat degree went from 4.4 to 30.6°C and the evaporating pressure changed from 40.0 to 51.2 bar. However, the gas cooler pressure also showed a significant increase, from 83.5 to 87.9 bar. To limit the raise of the superheat degree and to keep the compressor integrity, minor modifications are recommended. Altering from LSR to LSR+fan, an improvement of 17.2% on heating capacity was found, with no penalty to COP, showing that the addition of the fan is advantageous in low solar radiation conditions. Apart from the factorial design, additional runs were carried out to increase the number of experimental points to validate the capillary tube algebraic solution. Overall, the C-M&N friction factor demonstrated to be the best for the proposed solution. The percentual of mass flow rate points predicted within 10% and 15% error bands were 95% and 100%, respectively, for the best combination. |
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Raphael Nunes de Oliveirahttp://lattes.cnpq.br/0514681655241468Tiago de Freitas PaulinoLuiz MachadoJuan Jose Garcia PabónRalney Nogueria de FariaJuan José Garcoa Pabónhttp://lattes.cnpq.br/6378129638579747Thiago Torres Martins Rocha2021-05-17T17:08:03Z2021-05-17T17:08:03Z2020-03-13http://hdl.handle.net/1843/35980https://orcid.org/0000-0001-5449-3582Heat pumps are equipment used to promote space heating, to supply hot water or used for other heating purposes. The number of these systems should raise 16 times by 2050, as a contribution to meet the Paris agreement objectives. Despite presenting a relatively high efficiency, e.g. compared to electric resistance heaters, heat pumps still need to be developed. Direct-expansion solar-assisted heat pumps (DX-SAHP) are one alternative to improve the performance of air source heat pumps (ASHP). In this work, the behavior of a CO2 DX-SAHP is investigated under different operational conditions. However, the adjustable area expansion device (e.g. electronic expansion valve – EEV), generally used, was replaced by a capillary tube as an alternative to reduce the manufacturing costs. Initially, an algebraic solution to design an adiabatic coiled capillary tube operating in transcritical CO2 cycle was developed. Three different friction factors and three different k factors, related to the specific volume, were analyzed, creating a total of 9 possible combinations. After designing and assembling the tubes onto the workbench, tests were performed following a factorial design, with 2 different capillary tubes and 3 different operating conditions, namely: high solar radiation (HSR), low solar radiation (LSR), and low solar radiation with fan (LSR+fan). The results indicated an average augment of 57.9% on the heating capacity, 42.3% on COP, and 35% on the refrigerant mass flow rate, when changing from LSR (6 W/m²) to HSR (969 W/m²). The superheat degree went from 4.4 to 30.6°C and the evaporating pressure changed from 40.0 to 51.2 bar. However, the gas cooler pressure also showed a significant increase, from 83.5 to 87.9 bar. To limit the raise of the superheat degree and to keep the compressor integrity, minor modifications are recommended. Altering from LSR to LSR+fan, an improvement of 17.2% on heating capacity was found, with no penalty to COP, showing that the addition of the fan is advantageous in low solar radiation conditions. Apart from the factorial design, additional runs were carried out to increase the number of experimental points to validate the capillary tube algebraic solution. Overall, the C-M&N friction factor demonstrated to be the best for the proposed solution. The percentual of mass flow rate points predicted within 10% and 15% error bands were 95% and 100%, respectively, for the best combination.Bombas de calor são equipamentos usados para o aquecimento de ambientes, para o fornecimento de água quente ou para outros fins de aquecimento. O número desses sistemas deve crescer 16 vezes até 2050, para contribuir com os objetivos do acordo de Paris. Apesar de possuírem uma eficiência relativamente alta, elas ainda precisam de desenvolvimento. Bombas de calor assistidas por energia solar (DX-SAHP) são uma alternativa para melhorar o desempenho de bombas de calor à ar (ASHP). Neste trabalho, o comportamento de uma bomba de calor à CO2, DX-SAHP, é investigado sob diferentes condições operacionais. No entanto, o dispositivo de expansão ajustável (por exemplo, válvula eletrônica - EEV), geralmente utilizado, foi substituído por um tubo capilar como uma alternativa para a redução dos custos de fabricação. Inicialmente, uma solução algébrica para dimensionar um tubo capilar adiabático helicoidal, operando em ciclo de CO2 transcrítico, foi desenvolvida. Três diferentes fatores de atrito e três diferentes fatores k, relacionados ao volume especifico, foram analisados, criando um total de 9 possíveis combinações. Depois de dimensionar e montar os tubos capilares na bancada, testes foram realizados de acordo com o planejamento fatorial, com dois diferentes tubos capilares e 3 diferentes condições operacionais, a saber: alta radiação solar (HSR), baixa radiação solar (LSR) e baixa radiação solar com ventilador (LSR+fan). Os resultados indicaram um aumento médio de 57.9% na capacidade de aquecimento, 42.3% no COP e 35% na vazão mássica de refrigerante, quando se muda de LSR (6 W/m²) para HSR (969 W/m²). O grau de superaquecimento passou de 4.4 para 30.6°C, e a pressão de evaporação mudou de 40.0 para 51.2 bar. Mas a pressão no resfriador de gás também mostrou um aumento significativo, de 83.5 para 87.9 bar. Para limitar o aumento do superaquecimento e manter a integridade do compressor, pequenas modificações são recomendadas. Alterando-se de LSR para LSR+fan, ocorreu uma melhoria de 17.2% na capacidade de aquecimento sem penalização para o COP, mostrando que a adição do ventilador é vantajosa em baixas radiações solares. À parte do planejamento fatorial, testes adicionais foram realizados para aumentar o número de pontos experimentais para validar a solução algébrica do tubo capilar. Em geral, o fator de atrito C-M&N demonstrou ser o melhor para a solução proposta. Os percentuais de pontos de vazão mássica previstos dentro de faixas de erro de 10% e 15% foram 95% e 100%, respectivamente, para a melhor combinação.engUniversidade Federal de Minas GeraisPrograma de Pós-Graduação em Engenharia MecanicaUFMGBrasilENG - DEPARTAMENTO DE ENGENHARIA MECÂNICAEngenharia mecânicaBombas de calorControle de custoHeat pumpCost reductionCapillary tubeCO2DX-SAHPAlgebraic solutionExperimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tubeinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFMGinstname:Universidade Federal de Minas Gerais (UFMG)instacron:UFMGORIGINALDissertação versão final pdfa.pdfDissertação versão final pdfa.pdfDissertação versão final - Thiago Torres Martins Rochaapplication/pdf5453093https://repositorio.ufmg.br/bitstream/1843/35980/1/Disserta%c3%a7%c3%a3o%20vers%c3%a3o%20final%20pdfa.pdf511db51564fc5b0810ba23c7e88adf2eMD51LICENSElicense.txtlicense.txttext/plain; charset=utf-82119https://repositorio.ufmg.br/bitstream/1843/35980/2/license.txt34badce4be7e31e3adb4575ae96af679MD521843/359802021-05-17 14:08:03.765oai:repositorio.ufmg.br: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Repositório de PublicaçõesPUBhttps://repositorio.ufmg.br/oaiopendoar:2021-05-17T17:08:03Repositório Institucional da UFMG - Universidade Federal de Minas Gerais (UFMG)false |
dc.title.pt_BR.fl_str_mv |
Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube |
title |
Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube |
spellingShingle |
Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube Thiago Torres Martins Rocha Heat pump Cost reduction Capillary tube CO2 DX-SAHP Algebraic solution Engenharia mecânica Bombas de calor Controle de custo |
title_short |
Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube |
title_full |
Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube |
title_fullStr |
Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube |
title_full_unstemmed |
Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube |
title_sort |
Experimental study of a CO2 direct-expansion solar-assisted heat pump operating with an adiabatic coiled capillary tube |
author |
Thiago Torres Martins Rocha |
author_facet |
Thiago Torres Martins Rocha |
author_role |
author |
dc.contributor.advisor1.fl_str_mv |
Raphael Nunes de Oliveira |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/0514681655241468 |
dc.contributor.advisor-co1.fl_str_mv |
Tiago de Freitas Paulino |
dc.contributor.referee1.fl_str_mv |
Luiz Machado |
dc.contributor.referee2.fl_str_mv |
Juan Jose Garcia Pabón |
dc.contributor.referee3.fl_str_mv |
Ralney Nogueria de Faria |
dc.contributor.referee4.fl_str_mv |
Juan José Garcoa Pabón |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/6378129638579747 |
dc.contributor.author.fl_str_mv |
Thiago Torres Martins Rocha |
contributor_str_mv |
Raphael Nunes de Oliveira Tiago de Freitas Paulino Luiz Machado Juan Jose Garcia Pabón Ralney Nogueria de Faria Juan José Garcoa Pabón |
dc.subject.por.fl_str_mv |
Heat pump Cost reduction Capillary tube CO2 DX-SAHP Algebraic solution |
topic |
Heat pump Cost reduction Capillary tube CO2 DX-SAHP Algebraic solution Engenharia mecânica Bombas de calor Controle de custo |
dc.subject.other.pt_BR.fl_str_mv |
Engenharia mecânica Bombas de calor Controle de custo |
description |
Heat pumps are equipment used to promote space heating, to supply hot water or used for other heating purposes. The number of these systems should raise 16 times by 2050, as a contribution to meet the Paris agreement objectives. Despite presenting a relatively high efficiency, e.g. compared to electric resistance heaters, heat pumps still need to be developed. Direct-expansion solar-assisted heat pumps (DX-SAHP) are one alternative to improve the performance of air source heat pumps (ASHP). In this work, the behavior of a CO2 DX-SAHP is investigated under different operational conditions. However, the adjustable area expansion device (e.g. electronic expansion valve – EEV), generally used, was replaced by a capillary tube as an alternative to reduce the manufacturing costs. Initially, an algebraic solution to design an adiabatic coiled capillary tube operating in transcritical CO2 cycle was developed. Three different friction factors and three different k factors, related to the specific volume, were analyzed, creating a total of 9 possible combinations. After designing and assembling the tubes onto the workbench, tests were performed following a factorial design, with 2 different capillary tubes and 3 different operating conditions, namely: high solar radiation (HSR), low solar radiation (LSR), and low solar radiation with fan (LSR+fan). The results indicated an average augment of 57.9% on the heating capacity, 42.3% on COP, and 35% on the refrigerant mass flow rate, when changing from LSR (6 W/m²) to HSR (969 W/m²). The superheat degree went from 4.4 to 30.6°C and the evaporating pressure changed from 40.0 to 51.2 bar. However, the gas cooler pressure also showed a significant increase, from 83.5 to 87.9 bar. To limit the raise of the superheat degree and to keep the compressor integrity, minor modifications are recommended. Altering from LSR to LSR+fan, an improvement of 17.2% on heating capacity was found, with no penalty to COP, showing that the addition of the fan is advantageous in low solar radiation conditions. Apart from the factorial design, additional runs were carried out to increase the number of experimental points to validate the capillary tube algebraic solution. Overall, the C-M&N friction factor demonstrated to be the best for the proposed solution. The percentual of mass flow rate points predicted within 10% and 15% error bands were 95% and 100%, respectively, for the best combination. |
publishDate |
2020 |
dc.date.issued.fl_str_mv |
2020-03-13 |
dc.date.accessioned.fl_str_mv |
2021-05-17T17:08:03Z |
dc.date.available.fl_str_mv |
2021-05-17T17:08:03Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/1843/35980 |
dc.identifier.orcid.pt_BR.fl_str_mv |
https://orcid.org/0000-0001-5449-3582 |
url |
http://hdl.handle.net/1843/35980 https://orcid.org/0000-0001-5449-3582 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.publisher.none.fl_str_mv |
Universidade Federal de Minas Gerais |
dc.publisher.program.fl_str_mv |
Programa de Pós-Graduação em Engenharia Mecanica |
dc.publisher.initials.fl_str_mv |
UFMG |
dc.publisher.country.fl_str_mv |
Brasil |
dc.publisher.department.fl_str_mv |
ENG - DEPARTAMENTO DE ENGENHARIA MECÂNICA |
publisher.none.fl_str_mv |
Universidade Federal de Minas Gerais |
dc.source.none.fl_str_mv |
reponame:Repositório Institucional da UFMG instname:Universidade Federal de Minas Gerais (UFMG) instacron:UFMG |
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Universidade Federal de Minas Gerais (UFMG) |
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UFMG |
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UFMG |
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Repositório Institucional da UFMG |
collection |
Repositório Institucional da UFMG |
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