Novel heat recovery systems for building applications

The work presented in this thesis will explore the development of novel heat recovery systems coupled with low carbon technologies, and its integration to become one device with multifunction (building integrated heat recovery/cooling/air dehumidifier. In the first part of this thesis, an experimental performance of an individual heat recovery unit using Micro Heat and Mass Cycle Core (MHM3C) made of fibre papers with cross flow arrangement has been carried out. The unit was tested in an environmental control chamber to investigate the effects of various parameters on the performance of heat/energy recovery unit. The results showed that as the airflow rate and temperature change increase, the efficiency decreases whilst recovered energy increases. Integrating heat recovery system in energy-efficient system represents significant progress for building applications. As part of the research, the integration of heat recovery using a cross-flow fixed-plate with wind-catcher and cellulose fibre papers of evaporative cooling units have allowed part of the energy to be recovered with the efficiency of heat recovery unit ranged from 50 to 70%, cooling efficiency ranged from 31 to 54%. In another case, the integration of heat recovery system with building part so called building integrated heat recovery (BIHR) was explored using polycarbonate plate with counter-flow arrangement. It introduces a new approach to MVHR system, an established technology that uses a modified insulation panel, linking the inside and outside of a building, to recover heat while extracting waste air and supplying fresh air. In this configuration it is not only acts a heat recovery, but also as a contribution to building thermal insulation. From the experiments conducted, it was found that through an energy balance on the structure, the efficiency of BIHR prototype was found to be 50 to 61.1 % depending on the airflow rate. This efficiency increases to the highest value of 83.3% in a full-scale measurement on a real building in Ashford, Kent as the area of heat transfer surface increases. The increasing of heat surface area again proved a better performance in terms of efficiency as the results on another full scale measurement on a real house in Hastings, Sussex showed to be 86.2 to 91.7%. With the aiming to have a high performance system, a new improvement design of BIHR' corrugated polycarbonate channels with four airstreams has significant advantages over the previous prototype BIHR with two airstreams. The recovered heat is increased by more than 50%. With the issue of thermal comfort in hot region area and problems with conventional air conditioning system, a study of BIHR system with fibre wick structure for different hot (summer) air conditions using different working fluids was carried out. For the first case, water was used to give a direct evaporative cooling effect which is suitable to evaluate the system performance under hot and dry climatic conditions and the second case, potassium formate (HCOOK) solution was used as liquid desiccant for dehumidification under hot and humid climate conditions. By supplying the water over the fibre wick structure, with a constant airflow rate of 0.0157m3/s, the efficiency increased with increasing intake air temperature. The efficiency ranged from 20 to 42.4% corresponding to the minimum and maximum of intake air temperature of 25°C and 38.2°C, respectively. With the variation of airflow rate, the efficiency of the system was found to be 53.2 to 60%. In second case, the HCOOK solution with concentration of 68.6% has been selected as the desiccant and for a defined airflow rate of 0.0157m3/s, heat recovery efficiency of about 54%, a lower desiccant temperature of 20°C, with higher intake air temperature and relative humidity produces a better dehumidification performance with a good moisture absorption capacity. Therefore, this system is expected to be used efficiently in hot and humid regions. The research is novel in the following ways: • The development of multifunction device in one system; building integrated, heat recovery, cooling, desiccant dehumidification. • The design and development of BIHR is an advanced technology of building thermal insulation and heat recovery. The novel BIHR -fibre wick cooling/dehumidification system has the potential to compete with conventional air conditioning systems under conditions involving high temperature and high moisture load

Experimental investigations of polymer hollow fibre heat exchangers for building heat recovery application

Due to low cost, light weight and corrosion resistant features, polymer heat exchangers have been extensively studied by researchers with the aim to replace metallic heat exchangers in a wide range of applications. Although the thermal conductivity of polymer material is generally lower than the metallic counterparts, the large specific surface area provided by the polymer hollow fibre heat exchanger (PHFHE) offers the same or even better heat transfer performance with smaller volume and lighter weight compared with the metallic shell-and-tube heat exchangers. This paper presents the construction and experimental investigations of polypropylene based polymer hollow fibre heat exchangers in the form of shell-and-tube. The measured overall heat transfer coefficients of such PHFHEs are in the range of 258–1675 W/m2K for water to water application. The effects of various parameters on the overall heat transfer coefficient including flow rates and numbers of fibres, the effectiveness of heat exchanger, the number of heat transfer unit (NTU), and the height of transfer unit (HTU) are also discussed in this paper. The results indicate that the PHFHEs could offer a conductance per unit volume of 4 × 106 W/m3K, which is 2–8 times higher than the conventional metal heat exchangers. This superior thermal performance together with its low cost, corrosive resistant and light weight features make PHFHEs potentially very good substitutes for metallic heat recovery system for building application

Fundamental study in the heat and mass transfer of a membrane-based energy recovery for building applications.

In the past, researchers have focused on the recovery of sensible heat by utilising device such as heat-pipe and fixed plate energy recovery to be used in air conditioning system for building applications. However, these devices have limitations because of the lack of capability to transfer latent heat (moisture transfer). In order to recover both sensible and latent heat, rotary energy wheel have been used. Unfortunately, the major disadvantage of the rotary wheel is the greater cross-contamination between exhaust and fresh supply air. In addition to this, this device also needs a high cost and require maintenance

Design and development of a membrane-based energy recovery systm integrated with turbine ventilator for building application in hot-humid climate.

This project involves development of a novel energy recovery device coupled with turbine ventilator,and and its intergration to become one system with multifunction (hybrid design) in order to achieve integrated energy-efficient technology for building air-conditioning in hot-humid climate which is called hybrid erv. It consists of two phases in delivering the methodology framework which are: 1) design and development of a membrane-based energy recovery unit for building air-conditioning in hot-humid climate; and 2) performance investigation of integrated membrane-based energy recovery with turbine ventilator for building air-conditioning in hot-humid climate. The integrated design uses advanced materials and could provide the roof ventilation to negate heat and moisture problems for air-conditioned buildings and allow part of the energy from the return airflow to be recovered, thus improving energy efficiency and reducing environmental impact this research contributes to the knowledge of energy recovery for building applications as well as a greater insight into the coupling of the energy recovery in a mix-integrated energy-efficient system to achieve good indoor air quality and energy conservation

Novel heat recovery systems for building applications

The work presented in this thesis will explore the development of novel heat recovery systems coupled with low carbon technologies, and its integration to become one device with multifunction (building integrated heat recovery/cooling/air dehumidifier. In the first part of this thesis, an experimental performance of an individual heat recovery unit using Micro Heat and Mass Cycle Core (MHM3C) made of fibre papers with cross flow arrangement has been carried out. The unit was tested in an environmental control chamber to investigate the effects of various parameters on the performance of heat/energy recovery unit. The results showed that as the airflow rate and temperature change increase, the efficiency decreases whilst recovered energy increases. Integrating heat recovery system in energy-efficient system represents significant progress for building applications. As part of the research, the integration of heat recovery using a cross-flow fixed-plate with wind-catcher and cellulose fibre papers of evaporative cooling units have allowed part of the energy to be recovered with the efficiency of heat recovery unit ranged from 50 to 70%, cooling efficiency ranged from 31 to 54%. In another case, the integration of heat recovery system with building part so called building integrated heat recovery (BIHR) was explored using polycarbonate plate with counter-flow arrangement. It introduces a new approach to MVHR system, an established technology that uses a modified insulation panel, linking the inside and outside of a building, to recover heat while extracting waste air and supplying fresh air. In this configuration it is not only acts a heat recovery, but also as a contribution to building thermal insulation. From the experiments conducted, it was found that through an energy balance on the structure, the efficiency of BIHR prototype was found to be 50 to 61.1 % depending on the airflow rate. This efficiency increases to the highest value of 83.3% in a full-scale measurement on a real building in Ashford, Kent as the area of heat transfer surface increases. The increasing of heat surface area again proved a better performance in terms of efficiency as the results on another full scale measurement on a real house in Hastings, Sussex showed to be 86.2 to 91.7%. With the aiming to have a high performance system, a new improvement design of BIHR' corrugated polycarbonate channels with four airstreams has significant advantages over the previous prototype BIHR with two airstreams. The recovered heat is increased by more than 50%. With the issue of thermal comfort in hot region area and problems with conventional air conditioning system, a study of BIHR system with fibre wick structure for different hot (summer) air conditions using different working fluids was carried out. For the first case, water was used to give a direct evaporative cooling effect which is suitable to evaluate the system performance under hot and dry climatic conditions and the second case, potassium formate (HCOOK) solution was used as liquid desiccant for dehumidification under hot and humid climate conditions. By supplying the water over the fibre wick structure, with a constant airflow rate of 0.0157m3/s, the efficiency increased with increasing intake air temperature. The efficiency ranged from 20 to 42.4% corresponding to the minimum and maximum of intake air temperature of 25°C and 38.2°C, respectively. With the variation of airflow rate, the efficiency of the system was found to be 53.2 to 60%. In second case, the HCOOK solution with concentration of 68.6% has been selected as the desiccant and for a defined airflow rate of 0.0157m3/s, heat recovery efficiency of about 54%, a lower desiccant temperature of 20°C, with higher intake air temperature and relative humidity produces a better dehumidification performance with a good moisture absorption capacity. Therefore, this system is expected to be used efficiently in hot and humid regions. The research is novel in the following ways: • The development of multifunction device in one system; building integrated, heat recovery, cooling, desiccant dehumidification. • The design and development of BIHR is an advanced technology of building thermal insulation and heat recovery. The novel BIHR -fibre wick cooling/dehumidification system has the potential to compete with conventional air conditioning systems under conditions involving high temperature and high moisture load.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Utilization of Polymeric Materials toward Sustainable Biodiesel Industry: A Recent Review

The biodiesel industry is expanding rapidly in accordance with the high energy demand and environmental deterioration related to the combustion of fossil fuel. However, poor physicochemical properties and the malperformance of biodiesel fuel still concern the researchers. In this flow, polymers were introduced in biodiesel industry to overcome such drawbacks. This paper reviewed the current utilizations of polymers in biodiesel industry. Hence, four utilizing approaches were discussed, namely polymeric biodiesel, polymeric catalysts, cold-flow improvers (CFIs), and stabilized exposure materials. Hydroxyalkanoates methyl ester (HAME) and hydroxybutyrate methyl ester (HBME) are known as polymeric biodiesel sourced from carbon-enriched polymers with the help of microbial activity. Based on the literature, the highest HBME yield was 70.7% obtained at 10% H2SO4 ratio in methanol, 67 °C, and 50 h. With increasing time to 60 h, HAME highest yield was reported as 68%. In addition, polymers offer wide range of esterification/transesterification catalysts. Based on the source, this review classified polymeric catalysts as chemically, naturally, and waste derived polymeric catalysts. Those catalysts proved efficiency, non-toxicity, economic feasibility, and reusability till the 10th cycle for some polymeric composites. Besides catalysis, polymers proved efficiency to enhance the biodiesel flow-properties. The best effect reported in this review was an 11 °C reduction for the pour point (PP) of canola biodiesel at 1 wt% of ethylene/vinyl acetate copolymers and cold filter plugging point (CFPP) of B20 waste oil biodiesel at 0.08 wt% of EVA copolymer. Polymeric CFIs have the capability to modify biodiesel agglomeration and facilitate flowing. Lastly, polymers are utilized for storage tanks and auto parts products in direct contact with biodiesel. This approach is completely exclusive for polymers that showed stability toward biodiesel exposure, such as polyoxymethylene (POM) that showed insignificant change during static immersion test for 98 days at 55 °C. Indeed, the introduction of polymers has expanded in the biodiesel industry to promote green chemistry

Authentication of a selected medicinal plants using DNA barcoding technique

Plants are valuable source of a medicine and have long being used to cure various ailments. However, the efficacy of drugs derived from plant depends on the reliable identification of correct plants. To avoids the usage of incorrect plant that can cause poisoning, a reliable method than morphological characteristic is required. DNA barcoding technique have shown to be an efficient tool for species identification by using a short fragment of the genomic DNA and has been used widely in molecular plant taxonomy for authentication of medicinal plants species. Thus, the goal of this study was to use DNA barcoding technique to discriminate medicinal plants. DNA samples were extracted from twenty medicinal plants, chosen based on their therapeutic efficacy and were used as templates. Internal transcribed spacer (ITS2) gene was selected to be the best molecular marker for identification purposes. The efficiency of the amplification by polymerase chain reaction was sending for sequencing and species identification was performed using MEGA6. Our findings show that DNA barcoding is an efficient tool for plants identification. This study revealed that medicinal plant and their closely related species can be distinguished by using DNA barcoding technique with ITS2 region as it is an efficient marker and potential DNA marker for authentication of selected plants

Authentication of a selected medicinal plants using DNA barcoding technique

Plants are valuable source of a medicine and have long being used to cure various ailments. However, the efficacy of drugs derived from plant depends on the reliable identification of correct plants. To avoids the usage of incorrect plant that can cause poisoning, a reliable method than morphological characteristic is required. DNA barcoding technique have shown to be an efficient tool for species identification by using a short fragment of the genomic DNA and has been used widely in molecular plant taxonomy for authentication of medicinal plants species. Thus, the goal of this study was to use DNA barcoding technique to discriminate medicinal plants. DNA samples were extracted from twenty medicinal plants, chosen based on their therapeutic efficacy and were used as templates. Internal transcribed spacer (ITS2) gene was selected to be the best molecular marker for identification purposes. The efficiency of the amplification by polymerase chain reaction was sending for sequencing and species identification was performed using MEGA6. Our findings show that DNA barcoding is an efficient tool for plants identification. This study revealed that medicinal plant and their closely related species can be distinguished by using DNA barcoding technique with ITS2 region as it is an efficient marker and potential DNA marker for authentication of selected plants