Papers by Bin-Juine Huang
The present study intends to develop building-integrated solar collector (BISC). The storage tank... more The present study intends to develop building-integrated solar collector (BISC). The storage tank inside is designed in multi-function. BISC combines the solar collector and the water storage tank together with one face acting as the solar absorber. A double-glazing design is adopted to reduce the heat loss. A PC-based automatic operating system is designed and built to monitor the long-term performance of the BISC system with 8 collector units. Hot water discharge is controlled from 18:00 until 22:00 to simulate the hot water load of a family. The discharge rate is at 60 L/hr. A 30 L backup electric water heater was connected to the BISC system. The long-term test results in winter season show that about 50 % energy saving was achieved in clear days. The monitored results have also shown that the daily-total solar irradiation on a 75 o tilted surface (the BISC installed angle) is higher than the horizontal surface, about 40-50 % higher at Ht > 10 MJ/m^2day. This assures that BISC will produce more hot water in winter. This proves that the use of BISC as parapet or sun-shading canopy of a building (installation angle > 75 o) is technically feasible. The characteristic efficiency of the installed BISC with different colors is 0.34-0.39.
—The concept of red-green-blue (RGB) light-emitting-diode (LED) lighting has gained wide attentio... more —The concept of red-green-blue (RGB) light-emitting-diode (LED) lighting has gained wide attention during recent years and is now one of the targets for future lighting solutions. However, the self-heating of LEDs and environmental temperature variation lead to luminous intensity droop and lighting color drift. The main purpose of this research is to investigate a novel flux feedback and temperature feed-forward (FFB&TFF) control structure for RGB LED lighting control system, in order to provide a wide color range of input commands and regulation of both luminous and color outputs. The work in this paper was carried out in three main steps. First, a thermal–electrical–luminous–chromatic model was derived and identified for RGB LED luminaire. Second, a converter and a compensator were derived and applied to input command conversion and temperature compensation, respectively. Finally, a diagonal proportional–integral controller designed by the decentralized control approach was implemented to regulate the lighting outputs of luminous intensity and chromaticity coordinates in CIE 1976 Uniform Chromaticity Space (UCS) diagram. The results of transient and steady-state experiments showed that the proposed control system was effective. Index Terms—Decentralized control approach, flux feedback and temperature feed-forward (FFB&TFF), red-green-blue (RGB) light-emitting-diodes (LEDs), system identification, thermal– electrical–luminous–chromatic model.
A solar-assisted ejector cooling/heating system (SACH-2k) is built and test result is reported. T... more A solar-assisted ejector cooling/heating system (SACH-2k) is built and test result is reported. The solar-driven ejector cooling system (ECS) is connected in series with an inverter-type air conditioner (IAC). Several advanced technologies are developed in SACH-k2, including generator liquid level control in ECS, the ECS evaporator temperature control, and optimal control of fan power in cooling tower of ECS. From the field test results, the generator liquid level control performs quite well and keeps stable performance of ejector. The ECS evaporator temperature control also performs satisfactorily to keep ejector performance normally under low or fluctuating solar radiation. The fan power control system cooling tower performs stably and reduces the power consumption dramatically without affecting the ECS performance. The test results show that the overall system COP o including power consumptions of peripheral increases from 2.94e3.3 (IAC alone) to 4.06e4.5 (SACH-k2), about 33e43%. The highest COP o is 4.5.
• We design a multiple-effect diffusion solar still with a bended shape. • A vacuum-tube solar co... more • We design a multiple-effect diffusion solar still with a bended shape. • A vacuum-tube solar collector is used to produce high temperature for distillation. • A heat pipe is used to transfer solar heat for distillation. • A prototype MEDS-1L was built and tested outdoors. • MEDS-1L performs very well compared to other designs. a b s t r a c t The present study develops a multiple-effect diffusion solar still (MEDS) with a bended-plate design in multiple-effect diffusion unit (MDU) to solve the peel-off problem of wick material. The MDU is coupled with a vacuum-tube solar collector to produce a high temperature gradient for high productivity. A heat pipe is used to transfer the solar heat to the MDU. A prototype MEDS-1L was built and tested outdoors. Four performance indexes are proposed for the performance evaluation of MEDS, including daily pure water production per unit area of glass cover, solar absorber, and evaporating surface (M cov , M sol , M evp , respectively), and solar distillation efficiency R cov. The outdoor test results of MEDS-1L show that the solar collector supply temperature T h reaches 100 °C at solar radiation 800 W m −2. The highest M cov is 23.9 kg m −2 d −1 which is about 29% higher than the basin-type MEDS [11]. The highest value is 25.9 kg m −2 d −1 for M sol and 2.79 kg m −2 d −1 for M evp. The measured R cov is 1.5–2.44, higher than the basin-type MEDS (1.45–1.88). The M cov , M sol , M evp and R cov of MEDS-1L are all higher than the theoretical calculation of a MEDS with a flat-plate solar collector coupled with a heat pipe (MEDS-FHP) [17].
In a solar vapor ejector refrigeration system, the solar heat supply may vary because of variatio... more In a solar vapor ejector refrigeration system, the solar heat supply may vary because of variations in solar irradiation intensity, making it difficult to maintain a steady generator temperature. To improve ejector performance, this study proposes a variable throat ejector (VTEJ) and analyzes its performance using CFD simulations. The following conclusions can be drawn. An ejector with a greater throat area and larger solar collector allows a wider operating range of generator temperatures, but may be overdesigned and expensive. Conversely, decreasing the throat area limits the operating range of generator temperatures. Thus the ejector with a fixed throat area may be unsuitable to use solar energy as a heat source. For a VTEJ, this study derives a curve-fitting relationship between the optimum throat area ratio and the operating temperatures. Using this relationship to adjust the throat area ratio, the ejector can consistently achieve optimal and stable performances under a varying solar heat supply.
The energy conversion efficiency of commercial solar PV is around 15-19%. Millions of dollars are... more The energy conversion efficiency of commercial solar PV is around 15-19%. Millions of dollars are spent in order to gain a small percentage in energy conversion efficiency. The power generation of solar PV can be increased using sun tracking technology. However, the design of the sun tracker is usually very complicated and expensive. Units are heavy and prone to breakdown and installation is difficult. In the present study, one-axis three-position (1A-3P) low-cost sun tracking PV as a BIPV was developed and tested. The comparative test of a 1A-3P tracking PV system started from 2010/3/01 was carried out. The single-day increase of energy generation is 39% in clear days. The overall increase of total energy generation from March 1, 2010 to May 31, 2012, is 24.2% in Taipei. The expected overall increase of total energy generation with respect to fixed PV is 37.5% in high solar radiation areas. The installation cost of 1A-3P sun tracking PV is about the same as the regular mounting cost of a conventional rooftop PV system, but providing 25-37% higher PV energy generation efficiency. For cost reduction in structural design, the wall mounting of 1A-3P tracker may cause PV not facing south exactly. A long-term comparative field test was carried out to study the effect of misalignment using three identical 1A-3P tracking PV module facing south, southeast 45 o , and southwest 45 o. The measured energy loss is 4.42~6.82% for southeast orientation and 4.31~6.79% for southwest orientation. The test result shows that the energy loss of 1A-3P PV due to misalignment of south is negligible. Many samples of 1A-3P trackers were manufactured and installed for field test. The longest test is over 30 months with satisfactory performance.
< A constant-power driving technique is proposed for LED luminaire. < A linear system dynamics mo... more < A constant-power driving technique is proposed for LED luminaire. < A linear system dynamics model of LED luminaire is used in the control system design. < The test shows that the feedback system accurately controls the input power. < The LED illumination varies slightly (À1.7%) for constant-power driving. a b s t r a c t The illumination of an LED may be affected by operating temperature even under constant-current condition. A constant-power driving technique is proposed in the present study for LED luminaire. A linear system dynamics model of LED luminaire is first derived and used in the design of the feedback control system. The PI controller was designed and tuned taking into account the control accuracy and robust properties with respect to plant uncertainty and variation of operating conditions. The control system was implemented on a microprocessor and used to control a 150W LED luminaire. The test result shows that the feedback system accurately controls the input power of LED luminaire to within 1.3 per cent error. As the ambient temperature changes from 0 to 40 C, the LED illumination varies slightly (À1.7%) for constant-power driving, as compared to that of constant-current driving (À12%) and constant-voltage driving (þ50%). The constant-power driving has revealed advantage in stabilizing the illumination of LED under large temperature variation.
A direct battery-driven LED lighting technique using constant-power control is proposed in the pr... more A direct battery-driven LED lighting technique using constant-power control is proposed in the present study. A system dynamics model of LED luminaire was derived and used in the design of the feedback constant-power control system. The test result has shown that the power of 18 W and 100 W LED luminaires can be controlled accurately with error at 2–5%. A solar LED street lighting system using constant-power and dimming control was designed and built for field test in a remote area. The long-term performance was satisfactory and no any failure since the installation. Since no high-power capacitor is used in the present constant-power control circuit, a longer lifetime is expected.
The present study developed a maximum-power point tracking control (MPPT) technology for solar he... more The present study developed a maximum-power point tracking control (MPPT) technology for solar heating system to minimize the pumping power consumption at an optimal heat collection. The net solar energy gain Q net (=Q s À W p /g e) was experimentally found to be the cost function for MPPT with maximum point. The feedback tracking control system was developed to track the optimal Q net (denoted Q max). A tracking filter which was derived from the thermal analytical model of the solar heating system was used to determine the instantaneous tracking target Q max (t). The system transfer-function model of solar heating system was also derived experimentally using a step response test and used in the design of tracking feedback control system. The PI controller was designed for a tracking target Q max (t) with a quadratic time function. The MPPT control system was implemented using a microprocessor-based controller and the test results show good tracking performance with small tracking errors. It is seen that the average mass flow rate for the specific test periods in five different days is between 18.1 and 22.9 kg/min with average pumping power between 77 and 140 W, which is greatly reduced as compared to the standard flow rate at 31 kg/min and pumping power 450 W which is based on the flow rate 0.02 kg/s m 2 defined in the ANSI/ASHRAE 93-1986 Standard and the total collector area 25.9 m 2. The average net solar heat collected Q net is between 8.62 and 14.1 kW depending on weather condition. The MPPT control of solar heating system has been verified to be able to minimize the pumping energy consumption with optimal solar heat collection.
The present study develops a hybrid PV system (HyPV) which operates at stand-alone PV mode and gr... more The present study develops a hybrid PV system (HyPV) which operates at stand-alone PV mode and grid mode automatically and does not feed power into grid. HyPV operates at PV mode when solar radiation or battery energy is high enough. It switches to grid mode when battery storage is low. The switch scheme from grid to PV mode determines the system performance, including life of battery and switching device, and PV energy generation loss. A switching control parameter (S B , critical charge energy in grid mode) is defined as function of normalized excess PV power generation (e B) and used in the study. A system simulation was carried out to study the effect of switching schemes on long-term system performance. A HyPV system was built and tested to exam the field performance.
Solar air conditioning system directly driven by stand-alone solar PV is studied. The air conditi... more Solar air conditioning system directly driven by stand-alone solar PV is studied. The air conditioning system will suffer from loss of power if the solar PV power generation is not high enough. It requires a proper system design to match the power consumption of air conditioning system with a proper PV size. Six solar air conditioners with different sizes of PV panel and air conditioners were built and tested outdoors to experimentally investigate the running probabilities of air conditioning at various solar irradiations. It is shown that the instantaneous operation probability (OPB) and the runtime fraction (R F) of the air conditioner are mainly affected by the design parameter r pL (ratio of maximum PV power to load power). The measured OPB is found to be greater than 0.98 at instantaneous solar irradiation I T > 600 W m À2 if r pL > 1.71. R F approaches 1.0 (the air conditioner is run in 100% with solar power) at daily-total solar radiation higher than 13 MJ m À2 day À1 , if r pL > 3.
The ejector refrigeration machine (ERM) offers several advantages over other heat-driven refriger... more The ejector refrigeration machine (ERM) offers several advantages over other heat-driven refrigeration machine, including simplicity in design and operation, high reliability and low installation cost, which enable its wide application in the production of cooling. In this paper the theoretical analysis of ejector design and ejector refrigeration cycle performance is presented. It is shown that ERM performance characteristics depend strongly on the operating conditions, the efficiency of the ejector used, and the thermodynamic properties of the refrigerant used. A 1-D model for the prediction of the entrainment ratio u, and an optimal design for ejectors with cylindrical and conical-cylindrical mixing chambers are presented in this paper. In order to increase ERM performance values, it is necessary first of all to improve the performance of the ejector.
The present study develops a cooling system using water as the working medium which is cooled at ... more The present study develops a cooling system using water as the working medium which is cooled at night by cellulose-pad cooling tower (CWCT) and stored for cooling application at daytime. That is, it utilizes the natural energy drawn from diurnal ambient air temperature difference. A cooling system was built and tested. It is found that the coefficient of performance of CWCT for heat dissipation of water at night, COPnt, is between 3.8 and 11 and varies linearly with the evaporation temperature glide DG (difference between cold water temperature in the storage tank and wet-bulb temperature of ambient air). The COP for room cooling at daytime run with air cooler in a room, COPday, is between 8.8 and 12.6. For day cycle operation, the measured overall cooling COPo is 5.1. COPo is expected to reach 9.4 at room temperature 45 °C.
The main results of a theoretical and experimental investigation of the performance characteristi... more The main results of a theoretical and experimental investigation of the performance characteristics of an ejector and an ejector refrigeration machine (ERM) operating with refrigerant R245fa at design and off-design working conditions are presented. The ejector and ERM were explored theoretically using improved 1D model and the calculated results were validated experimentally on ejector test rig that has been assembled and operated at National Taiwan University. For typical cases, the performance characteristics variation with condensing, generating and evaporating temperatures along with performance maps are presented. The theoretical results are compared with the results of a set of experiments and good qualitative and quantitative agreement is observed.
We develop thermoelectric generator (TEG) using loop heat pipe and design for maximum power. TEG ... more We develop thermoelectric generator (TEG) using loop heat pipe and design for maximum power. TEG uses loop heat pipe to dissipate heat without consuming power and free of noise. TEG using design match for maximum-power generation performs better than TEG with MPPT. a b s t r a c t The present study focuses on the thermoelectric generator (TEG) using loop heat pipe (LHP) and design match for maximum-power generation. The TEG uses loop heat pipe, a passive cooling device, to dissipate heat without consuming power and free of noise. The experiments for a TEG with 4 W rated power show that the LHP performs very well with overall thermal resistance 0.35 K W À1 , from the cold side of TEG module to the ambient. The LHP is able to dissipate heat up to 110 W and is maintenance free. The TEG design match for maximum-power generation, called " near maximum-power point operation (nMPPO) " , is studied to eliminate the MPPT (maximum-power point tracking controller). nMPPO is simply a system design which properly matches the output voltage of TEG with the battery. It is experimentally shown that TEG using design match for maximum-power generation (nMPPO) performs better than TEG with MPPT.
• A spiral multiple-effect diffusion solar still is developed. • The measured water productivity ... more • A spiral multiple-effect diffusion solar still is developed. • The measured water productivity is higher than the published results. • The manufacture of spiral solar is easier and cheaper. a b s t r a c t A novel solar still with spiral-shape multiple-effect diffusion unit is developed in the present study. The test results of a 14-effect unit coupled with vacuum-tube solar collector (absorber area 1.08 m 2) show that the highest daily pure water production is 40.6 kg d −1. The measured highest productivity based on the area of glass cover, solar absorber, and evaporating surface is 34.7, 40.6, and 7.96 kg m −2 d −1 , respectively, which are much higher than the published results. The measured solar distillation efficiency is 2.0–3.5. The performance enhancement results mainly from the lateral diffusion process in the spiraled still cell. The vapor flow generated by heat input can flow freely and laterally through the spiral channel down to the end when solar heat input is high. Besides , the larger evaporating and condensing area at the outer cell may increase heat and mass transfer at the outer cell.
The thermal performance of a solar collector with intermittent output is investigated in the pres... more The thermal performance of a solar collector with intermittent output is investigated in the present paper. It is shown that a parameter derived from a simple theoretical modeling can be used to correlate the test results very well.
The similarity theory of solar thermosyphon collector is developed in the present paper. Ten dime... more The similarity theory of solar thermosyphon collector is developed in the present paper. Ten dimension-less groups or system characteristic parameters which uniquely determine the performance of the collector are derived. The solution shows that the mean efficiency generally increases with increasing incident solar radiation and relative height of the tank. For the frictional parameters N, and Nf higher than lO s, the efficiency appears to be independent of the incident radiation and the relative height of the tank. Therefore, for parallel plate absorber, the tank may be designed to sit on the floor without sacrificing the efficiency since the values of Ne and N I are usually larger than lOs in most designs.
model is developed to ~ the technical feasibility of mki deep autrimt-ri~h Jeawater for nmicelmre... more model is developed to ~ the technical feasibility of mki deep autrimt-ri~h Jeawater for nmicelmre end nudmr power plant
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Papers by Bin-Juine Huang