Heat Loss Test Research Articles

Capturing Building Fabric Thermal Performance and Solar Heat Gains Through a Whole House Heat Loss Test – an In-Situ Study in Poland

Determining a building’s “as built” heat loss coefficient (HLC) is one of the key starting points to understand the role of residents’ practices in heating or cooling-related energy consumption. It is also a starting point for white-box modelling of different behaviour scenarios within a given home environment. Co-heating test is a recognised experimental method to evaluate the building’s fabric thermal performance. It involves a quasi-stationary homogeneous heating experiment performed on an unoccupied dwelling. This paper discusses the results of a co-heating test carried out in a low-energy semi-detached house in Wrocław, Poland between 6th-12th December 2021. The periods of different types of solar operation are captured to evaluate HLC: night-time with no solar gains, daytime with direct solar gains, and daytime with only the diffuse component of solar radiation. Internal solar gains in the building are calculated using the TRNSYS simulation program, assuming detailed modelling of the radiation incident on the vertical partitions (including the anisotropy of the diffused radiation component and complex analyses of the sun path geometry inside the building). Based on the results, the HLC values excluding infiltration and ventilation corresponding to different solar operation types are calculated and compared. This contributes to a more nuanced understanding of HLC under different external conditions.

Effects of environmental temperature and humidity on evaporative heat loss through firefighter suit materials made with semi-permeable and microporous moisture barriers

The goal of this research was to understand how firefighter protective suits perform in different operational environments. This study used a sweating guarded hotplate to examine the effect of environmental temperature (20–45°C) and relative humidity (25–85% RH) on evaporative heat loss through firefighter turnout materials. Four firefighter turnout composites containing three different bi-component (semi-permeable) and one microporous moisture barriers were selected. The results showed that the evaporative resistance of microporous moisture barrier systems was independent of environmental testing conditions. However, absorbed moisture strongly affected evaporative heat loss through semi-permeable moisture barriers coated with a layer of nonporous hydrophilic polymer. Moisture absorption in mild environment (20–25°C) tests, or when testing at high humidity (>85% RH), significantly increased water vapor transmission in semi-permeable turnout systems. It was also found that environmental conditions used in the total heat loss (THL) test (25°C and 65% RH) produced moisture condensation in bi-component barrier systems, making them appear more breathable than could be expected when worn in hotter environments. Regression models successfully qualified the relationships between moisture uptake levels in semi-permeable barrier systems and evaporative resistance and THL. These findings reveal the limitations in relying on THL, the heat strain index currently called for by the NFPA 1971 Standard for Structural Firefighter personal protective equipment, and supports the need to measure turnout evaporative resistance at 35°C (Ret), in addition to THL at 25°C.

Heat network testing actualization

The paper analyzes the testing methods for the heat loss, hydraulic resistance and maximum temperature of the heat carriers. The tests are based on the availability of modern equipment and the requirements of regulatory and technical documentation. The relevance of this work is due to the imperfect requirements of the current regulatory and engineering legislation of the Russian Federation for testing heating networks of resource providers. Based on the data obtained, it is possible to assess the potential of the test methods and expenditures. Purpose : Consideration of existing methods and updating of heating network testing methods. Methodology : Theoretical heat and hydraulic loss analyses of the heating networks. The test results are taken into consideration. Research findings : The obtained data can be used to update the testing process and eliminate errors in the test methods. Practical implications : The obtained results will allow the resource providers to increase the test efficiency of heating networks. Value : The existing heat and hydraulic loss test methods of heating networks were developed and approved in 1998. This work is aimed at developing modern methods with the elimination of the shortcomings of the existing methods and implementation of the modern equipment.

Design of a small size PTC: computational model for the receiver tube and validation with heat loss test

In EU, the residential sector is responsible for the 40% of the total energy consumption. The integration of solar technologies in buildings is therefore necessary in order to reduce the use of fossil fuels. Concentrating collectors could offer an interesting solution but nowadays their application in buildings is rare due to high costs, large dimensions and complexity of the system. A novel small parabolic trough collector (PTC) has been conceived to overcome these limits and to allow the integration in buildings. The main features of realized prototype are the compact dimensions, strongly reduced compared to the PTC standards, and modularity. The paper deals with the numerical analysis necessary to design the concentrating collector properly and its validation with experimental results. An optical analysis has allowed to select the optimum values for the parameters of the parabola, aperture and rim angle. A thermo-fluid dynamics finite element model has been developed with Comsol Multiphysics, to analyse the relevant physical characteristics and to predict the performance of the receiver tube. The efficiency curve of the collector has been extracted. Successively a receiver tube has been built based on the indications of FEM model for what concerns geometry and materials. In order to evaluate the heat loss of the receiver and to validate the finite element model, a test bench has been realized. The results of off-sun heat loss tests on the receiver tube are reported for several temperatures. The computational model is in good agreement with experimental results and therefore it is validated.

Heat Loss Simulations in Rod Bundle Tests

Nuclear fuel performance is generally derived from large-scale rod bundle tests, which mainly include rod bundle critical heat flux (CHF) tests and rod bundle mixing tests under conditions of high pressure, high mass flux, and high power. Though few differences exist in the test section configuration and operation conditions, CHF tests and mixing tests generally share the same test loop, the same pressure-bearing housing, and similar flow channel designs. In rod bundle tests, the test section consists of an inner flow path with an outer surrounding chamber (outer chamber) filled with stagnant coolant. Depending on the operating conditions, the massive coolant in the outer chamber may become a significant source of heat loss/heat gain resulting from natural circulation in the outer chamber. The complex structure of the test section and variable conditions appear to be obstacles to heat loss/gain estimation.In the past, most of the calculations and discussions for heat loss/gain correction were based on a steady-state assumption without exploring the impacts of true heat loss/gain resulting from potential transient operation. That is, in rod bundle tests, in order to determine the heat loss characteristics, only single-phase heat loss tests were conducted under different temperature steady-state conditions. With the limited parameter measured, the transient behaviors of the outer chamber are not reflected. In addition, potential heat gain conditions are neglected in single-phase heat loss tests. Based on heat loss test data, a correlation between heat loss and temperature difference of the test section inlet and exit is often derived. Given this situation, in this paper, lumped-parameter analyses are conducted to evaluate the heat loss/gain trend. A system code is applied to simulate the test section and surrounding systems under typical CHF test conditions to explore heat loss/gain transient behaviors, respectively. Methods to minimize the heat loss/gain effect through the design and operating scheme are discussed at the end.

Collector characterisation and heat loss tests on a novel batch solar water heater with CPC reflector for households

ABSTRACTThis solar water-heating unit is an integration of the older concept of batch water heating with the modern trends in solar water-heating technologies i.e. incorporating a concentrator in the design. The concentrator used is the compound parabolic type (CPC) which is a non-imaging device having wider acceptance angle (64°) and supported on a wooden cradle, which comprises the two arms of the parabola. To suppress the heat loss, an air gap has been introduced in the arms of the CPC. The collector is a single larger diameter drum which serves both as an absorber and storage unit positioned at the focus of CPC. The parametric study of the model showed the thermal efficiency of the collector as high as 38% and maximum water temperature attained was 53°C. Heat loss tests performed on the collector on a 24-hr cycle period showed good long time performance estimates. The response time of collector computed and performance characteristic curve plotted to predict system response under any given conditions of solar insolation and ambient temperature.

An analysis of the heat loss and overheating protection of a cavity receiver with a novel movable cover for parabolic trough solar collectors

In this research, the effects of the novel movable cover on reducing heat loss and overheating protection of a cavity receiver for parabolic trough solar collectors were studied. The heat loss tests were carried out at different inlet temperatures and mass flow rates. A three-dimensional heat transfer model was developed and validated by the test data. Effects of ambient temperature, wind speed, inlet temperature, rotation angle of the collector and on-off state of the movable cover on heat loss were investigated. The heat loss of turning off the movable cover was less than that of turning on it. The heat loss reduction rate varied from 6.36% to 13.55%. Three tests of collecting solar energy all the time (control group), overheating protection with the methods of rotating the reflector and turning off the movable cover were conducted under similar weather conditions. The results showed that both the overheating protection methods were effective. However, the method of turning off the movable cover avoided rotating the reflector and re-tracking the sun later. The presented novel movable cover improved the thermal performance of cavity receivers remarkably in a simple way.

Comparison of whole house heat loss test methods under controlled conditions in six distinct retrofit scenarios

The accurate assessment of buildings to assess their performance across a range of parameters is an essential part of understanding both new and retrofit buildings. The growing understanding of the performance gap in terms of its assessment and characterisation relies on effective methods of analysis. Here, we evaluate an experimental whole house method, known as QUB. As with many whole building approaches the method establishes heat loss through transmission and ventilation losses.This study compares QUB against an alternative, established, whole house test known as coheating. It was applied in a whole house test facility under controlled conditions. The test property, a solid wall pre-1919 UK archetype, was retrofit using a set of commercially available products and then the retrofit was removed in stages. At each of these stages a QUB test, which commonly takes one night, and coheating test, which can take few weeks, were applied. The objective of the study was to provide a comparison between the new method and more established method in terms of accuracy.The two methods showed close agreement in terms of results, suggesting that the quicker test has great potential as a more practical and economic test. There were higher levels of uncertainty with the QUB method due to shorter measurement periods. The lack of full boundary conditions within the test facility should be considered a limitation in applying the findings directly to the field. However, this study indicates the potential for QUB in validating performance, warranting further investigation.

Design of the Compact Integral Effects Test Facility and Validation of Best-Estimate Models for Fluoride Salt–Cooled High-Temperature Reactors

The capability to validate integral transient response models is a key issue for licensing new reactor designs. The Compact Integral Effects Test (CIET 1.0) facility reproduces the thermal-hydraulic response of fluoride salt–cooled high-temperature reactors (FHRs) under forced- and natural-circulation operation. CIET 1.0 provides validating data to confirm the predicted performance of the direct reactor auxiliary cooling system, used for natural-circulation–driven decay heat removal in FHRs, under a set of reference licensing basis events. CIET 1.0 uses a simulant fluid, DOWTHERM A oil, which, at relatively low temperatures (50°C to 120°C), matches the Prandtl, Reynolds, and Grash of numbers of the major liquid salts simultaneously, at ~50% geometric scale and heater power under 27% of prototypical conditions. CIET 1.0 has been designed, fabricated, filled with DOWTHERM A oil, and operated. Isothermal pressure drop tests were completed, with extensive pressure data collection to determine friction losses in the system. The project then entered a phase of heated tests, from parasitic heat loss tests to more complex feedback control tests and natural-circulation experiments, with the ultimate goal of validating best-estimate FHR models using RELAP5-3D and the novel one-dimensional FHR Advanced Natural Circulation Analysis (FANCY) code. This paper introduces the scaling strategy, design, and fabrication aspects, and start-up testing results from CIET 1.0. The CIET 1.0 model in RELAP5-3D and FANCY is detailed, and verification and validation efforts are presented. For various heat input levels and temperature boundary conditions, mass flow rates are compared between RELAP5-3D and FANCY results, analytical solutions when available, and experimental data, for both single and coupled natural-circulation loops. The study shows that both RELAP5-3D and FANCY provide excellent predictions of steady-state natural circulation in CIET 1.0, with mass flow rates within 13% of experimental data, suggesting that both codes are good candidates for design and licensing of FHR technology.

Thermal Performance of a Single-Pass All-Glass Parabolic Trough Receiver

AbstractA novel single-pass all-glass parabolic trough receiver (SPAG-PTR) was developed and the parabolic trough solar collector with concentration ratio of 7.5 was built to investigate the thermal performance of the SPAG-PTR. The indoor heat loss tests were settled as well as the outdoor experiments in quasi-steady-state and transient-state test conditions. The heat loss per unit absorber area of the SPAG-PTR in the average absorber temperature from 100 to 287°C was within the range of 85–674 W/m2, which represents a better heat loss performance (−15%) upon the Sanle-3 receiver (Nanjing Sanle Electronic Information Industry Group, Nanjing, China). The experimental efficiency in transient state was within the range of 0.53–0.73 with the experimental relative error of approximately 3.6–6.5%. In addition, the experimental efficiency curve in quasi-steady-state was obtained. In quasi-steady-state, the experimental efficiency was approximately 0.65–0.71 when the inlet heat transfer fluid temperature was in ...

풍동실험과 화재실험을 통한 열감지기의 동작특성에 관한 연구

The heat detector detects heat in the fire and is an important core element of the automatic fire alarm system used generally for every fire prevention objects. The heat detector is distinguished in spot type and spread type and in spot type, there are differential and thermistor types. These heat detectors give a great influence on the loss of people and property according to the sensitivity of response such as operation time and operation temperature in actual fire and in overseas people apply it for the development of products that can be operated in the early stage of fire including certification, quality management, and comparison standard by introducing response time index through the theory of heat balance that considers the heat loss and ventilation tests. In Korea, the response time index is introduced and used in the head of sprinkler products, but it is not applied to the heat detector at present. It is necessary to introduce the response time index that shows the sensitivity of response of the heat detector the installation standard for the heat detector that the response time index is applied should be different according to the fire weight, danger degree of fire, and shape of buildings. Through this study, it tries to help reduce lives and property of people through the swift warning by installing detectors suitable for the building structure.

Post-construction thermal testing: some recent measurements

In the UK, it has become apparent in recent years that there is often a discrepancy between the steady-state predicted and the measured in situ thermal performance of the building fabric, with the measured in situ performance being greater than that predicted. This discrepancy or gap in the thermal performance of the building fabric is commonly referred to as the building fabric ‘performance gap’. This paper presents the results and key messages obtained from undertaking a whole-building heat loss test (a coheating test) on seven new-build dwellings as part of the Technology Strategy Board’s Building Performance Evaluation Programme. While the total number of dwellings involved in the work reported here is small, the results illustrate that a wide range of discrepancies in thermal performance was measured for the tested dwellings. Despite this, the results also indicate that it is possible to construct dwellings where the building fabric performs thermally more or less as predicted, thus effectively bridging the traditional building fabric performance gap that exists in mainstream housing in the UK.

Heat Loss Test and Estimate for the Large-scale Floating Roof Tank

The heat loss and surface temperature of the top surface and sidewall of large-scale floating roof tank is tested by the heat flow meter and surface temperature method. Based on the test data, the heat loss from the top surface is about twice more than that of the sidewall which means the top surface is the weakest insulation part of the floating roof tank. On the surface, the heat loss profile is in accord with the surface temperature distribution. Special attention is given on the calculation of thermal conductivity for the top surface and sidewall which finally deduced the total heat transfer coefficient of large floating roof tank. Moreover, the heat loss of floating roof tank in different working conditions is predicted. According to the calculation results, the level of 6m is regarded as a critical level determining the heat loss. And the centralization storage of oil is a more energy conservation storage pattern.

Experimental investigation of porous disc enhanced receiver for solar parabolic trough collector

In this article, experimental investigation of 15 m2 solar parabolic trough collector with porous disc enhanced receiver is carried out according to ASHRAE 93-1986 test procedure. Six different receiver configurations are developed and investigated to compare their performance. The performance of solar parabolic trough collector with two conventional and four porous disc receivers is characterized in terms of time constant, collector acceptance angle, peak performance, daily performance and heat loss tests. The tests are carried out for wide range of flow rates (100 L/h–1000 L/h) and weather conditions. Based on experimental investigation, the time constant of the parabolic trough collector is varied from 70 s to 260 s for different receiver configurations. The collector acceptance angle is determined for both un-shielded tubular receiver (USTR) and shielded tubular receiver (STR) as 0.58° and 0.68° respectively. The collector efficiencies are obtained as in the range of 63.9%–66.66% under ASHRAE standard test condition. Off-Sunset heat loss test is conducted to determine the steady state heat losses from the parabolic trough collector receiver. The heat losses from the parabolic trough collector are in the range of 455 W/m2–1732 W/m2 for average fluid temperature of Tamb + 30 °C. Stagnation temperature of the collector is obtained as 258 °C and 312 °C respectively for USTR and STR corresponding to direct normal insolation (DNI) of 786 W/m2 and 761 W/m2. Based on the above analysis, the porous disc enhanced receiver improves the performance of the parabolic trough collector significantly and it can be used effectively for process heat applications.

Performance characteristics of a two-stage CO2 heat pump water heater adopting a sub-cooler vapor injection cycle at various operating conditions

The objective of this study is to investigate the performance characteristics of an injection CO2 (carbon dioxide) HPWH (heat pump water heater) at various operating conditions. In the standard and standby heat loss test conditions, the performance of a two-stage CO2 HPWH adopting a SCVI (sub-cooler vapor injection HPWH) cycle was measured and analyzed by varying the compressor frequency, the water flow rate, and the injection ratio at various outdoor temperatures. In the standard tests at the outdoor temperature of −15 °C, the COP (coefficient of performance) of the optimized SCVI HPWH was 7.6% higher than that of the non-injection HPWH. During the standby loss tests at the water flow rate of 200 kg h−1, the COP of the optimized SCVI HPWH was 7.1% higher than that of the non-injection HPWH.

An experimental study of thermal characterization of parabolic trough receivers

The receiver is a key component of the parabolic trough solar station. The receiver requires the most challenging technology and has a decisive influence on the thermal and economic performance of a power plant. The Institute of Electrical Engineering Chinese Academy Sciences (IEECAS) and Himin Solar Co., Ltd. (HSC) cooperated to develop solar receivers for the first 50MW parabolic trough project in Inner Mongolia, China. This paper examines overall heat loss, end loss and thermal emittance of the coating of a newly designed receiver in order to evaluate its thermal characterization. A series of heat loss tests are conducted in a newly developed test stand following the steady state equilibrium method. The tests provide a correlation between heat loss and the absorber temperature. This paper presents a new testing method to accurately test the coating emittance. The method uses a receiver with a high vacuum system and a vacuum gauge to maintain continuous exhaust and high vacuum throughout the heat loss testing. A heat loss comparison between the receiver and other existing receivers provides a reference that enabled further optimization. Theoretical and experimental analysis examines the effects of end loss both with and without a heat insulator and a coil heater. The emittance curves of different coatings are acquired and the reasons for initial emittance decrease and then remarkable increase versus temperature are analyzed.

An Update of the Development of Carbon Dioxide Removal System from the Flue Gas of Coal Fired Power Plant in Toshiba

Most CO2 removal systems at the thermal power plants demand the vast energy of the steam for the power generation, which lowers the performance and increases the cost. Therefore reducing the energy consumption is inevitable for introducing the CO2 removal system into the thermal power plant.We have achieved the energy consumption of 2.6GJ/t-CO2 at a condition of 90% CO2 capture ratio at our 10t-CO2/day pilot plant in February 2011 using the flue gas from the coal fired boiler of the Mikawa power plant. This is the first time in the world that the consumed energy of much lower than 3.0 GJ/t-CO2 has been proved at a 10t- CO2/day scale pilot plant using the actual flue gas of the coal fired power plant, not only by simulations. According to the heat loss test and analysis, it would be reduced more 0.3 GJ/t-CO2 by reinforcing the thermal insulation, which means 2.3GJ/t-CO2 would be possible at larger scale commercial plant.Since the pilot plant had completed in September 2009, we have been operating it continuously using the flue gas from the coal fired boiler. Then we have reached the 6,809 hour cumulative operating time which includes more than 3,000 hour operating time exceeding the planning values of 10t-CO2/day and 90% CO2 capture ratio. This means our excellent solvent called TS-1 (Toshiba Solvent 1) has enhanced durability and reliability because any definite degradation by SOX, NOX and oxidization has not been emerging during the operation.Furthermore we are reconstructing the pilot plant again and planning the next performance test starting in March 2012 targeting the less energy consumption.

A systematic study of the residual gas effect on vacuum solar receiver

A parabolic trough solar receiver is the key component in the parabolic trough solar system. The annulus between the absorber and glass envelope is evacuated to protect the solar selective coating and decrease the heat loss of entire receiver. However, at any existing operational solar plants, the vacuum condition in annulus may be compromised by glass breakage, seals and bellows broken, hydrogen penetration and getter decomposition. In this paper, different heat transfer mechanisms due to variable residual gas conditions in the annulus are analyzed. In addition, a series of heat loss tests of China’s first high temperature vacuum solar receiver are carried out by two methods with special exhaust system and vacuum gauges. The negative effects of residual gas, including environmental-sensitivity enhancement, coating degradation, and system efficiency decreasing, are acquired and analyzed with theoretical as well as test results.

Performance studies of two discrete mirror, seasonally-adjusted, linear solar concentrators

The optical and thermal performance of two discrete mirror, seasonally-adjusted, linear solar concentrators, with tubular and triangular absorbers, fabricated using locally available materials have been studied. The local concentration ratio distribution over the absorbers is obtained by performing flux mapping experiments at full moon. The optical efficiencies of the concentrators are found by no heat loss test. The time constants for both the systems have been measured. The heat loss coefficients at different temperatures are determined by performing heat loss test at the outside. All day performance test for both the concentrators has been conducted on a clear day and a semi-cloudy day. The results of the above experiments are presented graphically and discussed.

Estimation of hemispherical total emittance of tubular absorber from heat loss tests

The hemispherical total emittance of a selective coating on a tubular absorber is determined from the heat-loss factor obtained by an indoor test set-up. For this an analytical equation has been developed for the heat-loss factor of a tubular absorber with a concentric glass cover in the case of natural convection over the cover.