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Abstract The global production of poultry is predicted to grow considerably in the future. Intensive poultry farming poses significant challenges to traditional waste disposal methods (i.e. direct land application) leading to environmental impacts. This paper discusses the result of low temperature (350-450 °C) pyrolysis of representative chicken litter as the feedstock. Four different feedstocks comprised of 50% organic chicken manure and 50% bedding materials (i.e. hay, straw, rice husk and wood shavings) have been experimentally investigated. The products of the pyrolysis process consist of char, gas and liquid (bio-oil). Maximum char production from the rice husk mix is over 67 wt.%, while the wood shavings mix feedstock resulted in the highest liquid yield of 44.4 wt.% at a temperature of 400 °C. Chicken litter and its char product are analysed by elemental analyser and bomb calorimetry. The composition of the evolved gases and bio-oil are analysed by micro gas chromatography (µ-GC) and gas chromatography-mass spectrometry (GC-MS), respectively. In addition, the mass and energy balance of the pyrolysis process are presented. [ABSTRACT FROM AUTHOR]

In this study, a small-scale recuperative Organic Rankine Cycle (ORC) system capable of generating electric power using low-grade thermal energy was setup and experimentally investigated at different operating conditions. The experimental setup consisted of typical recuperative ORC system components, such as a turboexpander with high speed electricity generator, plate recuperator, finned-tube air cooled condenser, ORC fluid pump and plate evaporator. R245fa was used as the working fluid in the recuperative ORC system due to its zero ozone depletion potential (ODP) and appropriate thermophysical properties for ORC system. The working fluid was evaporated in a plate evaporator by hot thermal oil flow which was circulated and heated by exhaust flue gases of an 80kWe microturbine CHP unit. The test rig was fully instrumented and extensive experiments were carried out to compare and examine the influences of various important parameters including heat source temperature and ORC pump speed etc. on the performances of ORC systems with and without recuperator integration. The test results are essential in understanding the system operations and can contribute significantly to optimal system design, component selections and controls. [ABSTRACT FROM AUTHOR]

In CO 2 refrigeration systems, the system can operate in subcritical or transcritical cycle depending on ambient temperature. When the system is operating in transcritical cycle the heat exchanger at the high-pressure side of the system is well known as gas cooler. The gas cooler rejects heat from the superheated refrigerant gas to ambient air without condensation in single phase heat transfer process. The understanding of its performance parameters under different conditions and control strategies is essential to adequately design and optimise for specific applications. In this paper, a detailed mathematical model is developed in the Engineering Equation Solver (EES) platform, and validated with experimental results obtained from a test rig at the National Centre for Sustainable Energy use in Food Chains (CSEF). The model is investigated two different gas cooler designs when separately installed and test into a CO 2 refrigeration system, an attempt to formulate the design guidelines for CO 2 gas coolers. Then the detailed gas cooler models were integrated with the CO 2 refrigeration system model to investigate the effects of the gas cooler design into system COP. Parameters such as intermediate pressure, evaporating temperature and cooling capacity were defined from the experimental results and then inserted to the model. The results of the detailed gas cooler model and CO 2 refrigeration system model were validated against the experimental test results based on the gas cooler performance and overall system performance. [ABSTRACT FROM AUTHOR]

The paper describes an innovative design of open display cabinet’s shelves, based on flat heat pipe technology is presented. Their influence on the energy consumption of the cabinet and their effect on enhancing the preservation conditions of food products are analyzed. The experimental work was carried out using two identical commercial open display cabinets; one cabinet equipped with conventional/commercial shelves while the other one equipped with the new actively-cooled flat heat pipe shelves. Both cabinets were placed inside an ISO-certified environmentally controlled test chamber and experiments were carried out under stable environmental conditions. Food block simulators and real food products were used for the tests. The temperature distribution inside the real food products and the power consumption of the cabinets were measured for the cabinets’ set point of 2.0°C. The experimental outcomes were that the use of the heat pipe shelves can homogenize the temperature profile of the products and improve the heat transfer between the cabinet, the shelves and the products. Moreover, the heat pipe shelves facilitated the reduction of the electrical energy consumption of the cabinet by 12% approximately. Finally, a primary of the acidity levels (pH) of the products was conducted. The experiments showed that almost all products placed on the heat pipe shelves, after 20 days of experiments, had almost the same pH values, even 20 days beyond their expiration date. [ABSTRACT FROM AUTHOR]

This work conducted an experimental investigation of a small-scale organic Rankine cycle (ORC) system at designed operating and control conditions for low-grade thermal energy recovery application. In the ORC system, R245fa was selected as working fluid while a turboexpander (turbine) with a high speed and permanent magnet synchronous electricity generator was installed to produce electric power and two-plate type heat exchangers were designed as an evaporator and condenser. The effects of condenser cooling water temperatures and R245fa superheat at the turbine inlet on the system performance were measured and analyzed. Practically, to ensure safe operation of the ORC expander, the R245fa superheat at the expander inlet is controlled to remain constant. The experimental results showed that at constant heat source parameters (temperature and flow rate), the turboexpander power output and cycle efficiency increased with lower cooling water temperatures. Under the specified test condition ranges, the maximum turboexpander power generation could achieve 5.405 kW when the cooling water temperature and the pressure ratio were set at 23.0 °C and 7.3 respectively. On the other hand, at certain cooling water temperatures, the superheat at the expander inlet exerted a negative impact on the turboexpander and system performances when the evaporating pressure was kept constant. Ultimately, the superheat was found to be an important control parameter to ensure efficient and safe system operation. [ABSTRACT FROM AUTHOR]

Globally, there is no shortage of low-grade waste and renewable heat sources that can be converted into electricity and useful heat using applicable thermodynamic power cycles and appropriate working fluids. As a natural working fluid, CO 2 is a promising candidate for application in low-grade power generation systems but require optimised design and evaluation. Since CO 2 working fluid has a low critical temperature (31.1̊C) and high critical pressure (73.8 bar), a CO 2 low-grade power generation system will most likely undergo supercritical Rankine (T-CO 2 ) cycles. A T-CO 2 system normally consists of a CO 2 supercritical gas heater, expander, recuperator, condenser and liquid pump with the CO 2 gas heater being a crucial component in determining system thermal and exergy efficiencies. In this paper, the models of a thermal oil-CO 2 plate gas heater has been developed and validated with measurements of a 5 kW e T-CO 2 system test rig. The model is then integrated with other system component models to establish the system model. The system model can be used to evaluate and compare system performances at different operating conditions, including variable CO 2 gas heater pressures and heat sink parameters, thereby optimising system operations. [ABSTRACT FROM AUTHOR]

As a natural working fluid, CO 2 has been widely applied in refrigeration and heat pump systems where heat is conventionally rereleased to ambient through external airflow. Owing to extraordinary thermophysical properties, especially its low critical temperature, the CO 2 heat release through a high-pressure side heat exchanger will inevitably undergo either supercritical or subcritical processes, depending on ambient air temperatures and head pressure controls. Correspondingly, the heat exchanger will act intermittently as either a gas cooler or condenser within the system during an annual operation. Such evidence should therefore be taken into account for an optimal design of the heat exchanger and head pressure controls in order to significantly enhance the performance of both components and the associated system. To achieve these targets, two CO 2 finned-tube gas coolers/condensers with different structural designs and controls have been purposely built, instrumented and connected with an existing test rig of a CO 2 booster refrigeration system. Consequently, the performance of the CO 2 gas coolers/condensers with different structure designs, controls and system integration at different operating conditions can be thoroughly investigated through experimentation. In the meantime, models of the finned-tube CO 2 gas coolers/condensers have been developed using both the distributed (detailed model) and lumped (simple model) methods. The former is employed to give a detailed prediction of the working fluid temperature profiles, localized heat transfer rates and effects of pipe circuitry arrangements, while the latter is suitable for the simulation and optimisation of system integration with less computation time. Both models have been validated with measurements, and moreover the simple model has been integrated with other component models so as to create a system model. The effects of the CO 2 gas cooler/condenser sizes and controls on the system performance can thus be compared and analysed. [ABSTRACT FROM AUTHOR]

This paper reports on the energy performance evaluation of a displacement ventilation (DV) system in an airport departure hall, with a conventional DV diffuser and a diffuser retrofitted with a phase change material storage heat exchanger (PCM-HX). A TRNSYS-CFD quasi-dynamic coupled simulation method was employed for the analysis, whereby TRNSYS® simulates the HVAC and PID control system and ANSYS FLUENT® is used to simulate the airflow inside the airport terminal space. The PCM-HX is also simulated in CFD, and is integrated into the overall model as a secondary coupled component in the TRNSYS interface. Different night charging strategies of the PCM-HX were investigated and compared with the conventional DV diffuser. The results show that: i) the displacement ventilation system is more efficient for cooling than heating a space; ii) the addition of a PCM-HX system reduces the heating energy requirements during the intermediate and summer periods for specific night charging strategies, whereas winter heating energy remains unaffected; iii) the PCM-HX reduces cooling energy requirements, and; iv) maximum energy savings of 34% are possible with the deployment of PCM-HX retrofitted DV diffuser. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on a validation study of CFD models used to predict the effect of PCM clay boards on the control of indoor environments, in ventilated and non-ventilated situations. Unlike multi-zonal models, CFD is important in situations where localised properties are essential such as in buildings with complex and large geometries. The employed phase change model considers temperature/enthalpy hysteresis and varying enthalpy–temperature characteristics to more accurately simulate the phase change behaviour of the PCM boards compared to the standard default modelling approach in the commercial CFD codes. Successful validation was obtained with a mean error of 1.0 K relative to experimental data, and the results show that in addition to providing satisfactory quantitative results, CFD also provides qualitative results which are useful in the effective design of indoor thermal environment control systems utilising PCM. These results include: (i) temperature and air flow distribution within the space resulting from the use of PCM boards and different night ventilation rates; (ii) the fraction of PCM experiencing phase change and is effective in the control of the indoor thermal environment, enabling optimisation of the location of the boards; and (iii) the energy impact of PCM boards and adequate ventilation configurations for effective night charging. [Copyright &y& Elsevier]