Wey H. Leong's research while affiliated with University of Toronto and other places

Publications (67)

Article
Full-text available
In an attempt to further simplify and to refine the modelling of soil thermal conductivity (λ), two novel weighted average models (WAMs) were developed in which soil solids represent the continuous phase. In the first model, WAMs-1, the continuous phase consists of two distinctive minerals groups (quartz and compounded remaining soil minerals), whi...
Conference Paper
Full-text available
This study is conducted to analyze the working of borehole thermal energy storage (BTES) with a supercritical organic Rankine cycle (ORC). The new fluid R1123 is examined under different parameters like source temperature, evaporation pressure, evaporation temperature, work of the cycle components, mass flowrate and the heating load produced. The g...
Article
The thermal conductivity (λ) of soils is an important property in a variety of science and engineering applications. One of the most widely used λ models in soil science was proposed by de Vries (deV‐0). This model is complicated and difficult to use as it is based on several controversial assumptions. The deV‐0 assumes that a soil system is compos...
Article
To avoid the catastrophic results of climate change, a major shift towards clean, sustainable and renewable energy technologies is inevitable. Since buildings are capable of on-site thermal energy generation and exhibiting predictive patterns of heating and cooling, many attempts are currently underway to incorporate more renewable energy (e.g., ge...
Article
A comprehensive analysis of 6-published and 15-new Kersten (Ke) functions, i.e. normalized soil thermal conductivity (λ) expressions, was conducted using a complete λ data base of 40 Canadian soils. It was confirmed that Ke depended mainly on the degree of soil saturation (Sr), while additional dependency on volumetric content of sand (θsa) as the...
Article
Radiant floor systems have the potential to reduce energy consumption and the carbon footprint of buildings. This study analyzed a novel radiant panel configuration comprising a metal plate with small spikes that can be pressed into cement board or wood. The behavior of this configuration was simulated for different materials for the metal plate, s...
Article
A hybrid ground-coupled heat pump (GCHP) is an efficient and sustainable technology for space heating and cooling. A demonstration house equipped with GCHP with a solar seasonal heat storage (SSHS) system had been built in Harbin, a severe cold zone of China. A dynamic simulation model was built for the house and GCHP with the SSHS system using TRN...
Article
Full-text available
In an effort to reduce fossil fuel consumption and greenhouse gas emissions in the Canadian residential sector for space heating, a first-of-its-kind seasonal solar high-temperature borehole thermal energy storage (BTES) with district heating system for a community of 52 houses was built and has been in operation in Okotos, Alberta, Canada since 20...
Article
Ground source heat pump systems that are installed in areas with heating or cooling dominant seasons, or in buildings with utilization characteristics that lead to a disparity in demand, often encounter challenges related to ground thermal imbalance. This imbalance can lead to long-term ground temperature changes and may cause premature system fail...
Article
The performance of a new type of Air Source Heat Pump Water Heater (ASHPWH) has been investigated. ASHPWH has a better performance than the conventional electric water heater if it is installed in a hotter climate. However, the conditions are different in Canada, where outside air temperature is well below the freezing point for several months, and...
Article
Full-text available
Ground-coupled heat pump (GCHP) is an efficient and sustainable air-conditioning technology. A demonstration house equipped with ground-coupled heat pump with solar seasonal heat storage (GCHPSSHS) system in severe cold zone has been carried out in Harbin, China. A dynamic simulation model using TRNSYS has been built for the house equipped with GCH...
Conference Paper
Full-text available
Air Source Heat Pump Water Heater (ASHPWH) is a relatively new addition toproducing hot water at relatively high efficiency and it has achieved a market acceptance in several countries. This paper presents the experimental and simulation studies of an ASHPWH system that was recently installed and tested at the Archetype Sustainable House, Kortright...
Conference Paper
Air Source Heat Pump Water Heater (ASHPWH) is a relatively new addition for delivering hot water at reasonable high efficiency. However, ASHPWH undergoes a considerable drop in its coefficient of performance (COP) under cold conditions and may face challenges to maintain the water temperature in the storage tank at over 55 ⁰C. In this paper, an inv...
Article
Full-text available
The paper reveals the experimental procedure and thermo-physical charac-teristics of a coarse pyroclastic soil (Pozzolana), from the neighborhoods of Rome,Italy. The tested samples are comprised of 70.7 % sand, 25.9 % silt, and 3.4 % clay.Their mineral composition contained 38 % pyroxene, 33 % analcime, 20 % leucite,6 % illite/muscovite, 3 % magnet...
Article
Hybrid ground-source heat pumps (GSHPs) that include a ground loop for the base heating and cooling needs, and an auxiliary system (natural gas boiler and electric air conditioner) for peak loads, are an economical and environmentally cleaner alternative to conventional systems. For a ground-source heat pump (GSHP) system, the choice of entering fl...
Article
Full-text available
An advanced geometric mean model for predicting the effective thermal conductivity (\(\lambda \)) of unsaturated soils has been developed and successfully verified against an experimental \(\lambda \) database consisting of 40 Canadian soils, 15 American soils, 10 Chinese soils, four Japanese soils, three standard sands, and one pyroclastic soil (P...
Article
Two new mathematical models (with and without thermal contact resistance) to describe the behavior of a particular thermal conductivity probe (TCP) have been developed and analyzed together with experimental data of agar and Ottawa sand (C109) obtained by Tarnawski et al. (2009, 2011, 2013). One of the models has been studied in a previous companio...
Article
A new solution to the radial transient heat conduction has been developed for analyzing a thermal conductivity probe (TCP). The new analytical solution can better approximate the temperature responses than those from the classical solution of Carslaw and Jaeger (1959) when numerical results are compared with. Firstly, this paper theoretically analy...
Article
Forty field soil samples, from nine Canadian Provinces, were laboratory tested for their ability to conduct heat, i.e., thermal conductivity (), using a non-stationary probe technique. The measurements were carried out on moderately compacted samples at room temperature, and over a full range of degree of saturation ( ranging from dryness to full s...
Article
Growing demands for space heating and cooling make ground-source heat pump (GSHP) systems a viable renewable alternative. The economic outlook of potential installations can be addressed by hybridizing GSHP systems with an auxiliary system. To better understand optimization factors in sizing hybrid GSHP systems, a series of sensitivity analyses hav...
Article
In this study, the appropriateness of combining multiple buildings onto a single district hybrid GSHP system is assessed. For this purpose, a new methodology is introduced enhancing and utilizing a methodology previously introduced by the same authors for designing hybrid GSHP systems [Alavy et al., Renewable Energy 57 (2013) 404-412]. The new meth...
Article
Phase-change materials (PCMs) can be implemented into building practice to enhance thermal storage performance, reduce indoor temperature fluctuations, and improve the thermal comfort of occupants. As building energy simulation is taking an ever larger role in the design and analysis of energy-efficient buildings, it is important to understand the...
Article
This study demonstrates the importance of proper design of a vertical ground heat exchanger according to weather conditions. The geographical change in weather should be considered while designing for ground-source heat pump systems. Therefore, comparisons of a house utilizing a ground-source heatpump with a vertical ground heat exchanger were made...
Article
As an alternative energy technology, Ground Source Heat Pump (GSHP) systems offer greener advantages over conventional heating and cooling systems. This has led to their penetration not only in the residential building market, but also increasingly in commercial and industrial ones as well. However, longer payback periods, lesser return on investme...
Article
The results are reported of an experimental investigation of the soil thermal conductivity over a wide temperature range, for various water contents and two soil types. The results are particularly important in predictions of underground heat transfer, which require a quantitative understanding of the coupled dependence of the soil thermal conducti...
Article
The thermal conductivity (λ ) of three unsaturated standard quartz sands (Ottawa C-109 and C-190, and Toyoura) was measured by a transient thermal-conductivity probe, at room temperature of approximately 25° C and at loose and tight compactions. The measurements were carried out at different degrees of saturation (S_r) from dryness to full saturati...
Article
This document presents a study for examining the viability of hybrid ground source heat pump (GSHP) systems that use solar thermal collectors as the supplemental component in heating dominated buildings. Loads for an actual house in the City of Milton near Toronto, Canada, were estimated. TRNSYS, a system simulation software tool, was used to model...
Article
This chapter deals with the computer modelling and analysis of a ground source heat pump system, applied to building heating and cooling. The system performance is analyzed using the energy analysis approach. Simulation of ground source heat pump systems uses concurrent models of building heating/cooling loads, a heat pump unit, and heat transfer a...
Article
The effective thermal conductivity of unsaturated soils was estimated by an enhanced series-parallel model of conduction heat flow through a unit cell of soil. The cell is composed of three heat flow paths: solid contacts, solids + miniscule pores (filled with air and water, both parallel to heat flow direction), and a fluid path (water and air). T...
Article
The measured mineral composition data (XRD/XRF) of 40 Canadian soils were modeled for the presence of quartz as a function of soil texture. Preliminary modeling revealed a lack of strict correlation between quartz content and mass fraction of sand. For that reason, the occurrence of quartz content was modeled as dependent on a combined fraction of...
Article
Full-text available
This paper presented a novel hybrid solar GSHPS (HSGSHPS) composed of a GSHPS and a solar assisted GSHPS (SAGSHPS) used in an office building for heating and cooling. The key issues of designing the HSGSHPS were introduced and a simulation model was developed in TRNSYS to predict the multi-year performance of this system. The simulated results show...
Article
Forty Canadian soils were laboratory tested for the presence of quartz and other minerals using X-ray diffraction/X-ray fluorescence techniques. On average, the highest quartz content was observed in soil samples from sites in Nova Scotia followed by Prince Edward Island sites, whereas soil sample from British Columbia sites had the lowest quartz c...
Conference Paper
There is a requirement now within residential and commercial building sectors to be as energy efficient as possible. Government organizations are issuing more stringent energy efficiency regulations, including the mandatory energy efficiency requirements in the National Building Code of Canada (NBC); supplementary SB-10 code requirements in the Ont...
Conference Paper
The objective of this paper is to investigate the performance of two different types of Solar Domestic Hot Water (SDHW) systems, one with a gas boiler as the auxiliary heating source and the other with an electric tank as the auxiliary heating source, and to investigate the contributions of different components of the systems in lowering the annual...
Article
A non-stationary thermal probe technique was used to measure the thermal conductivity of three saturated standard sands (Ottawa sand C-109, Ottawa sand C-190, and Toyoura sand) in a range of soil porosities (n) from 0.32 to 0.42, and temperatures (T) from 25 °C to 70 °C. The sand thermal conductivities at full saturation (λ sat) increased with decr...
Article
A TRNSYS model of a demonstration house equipped with a solar assisted ground coupled heat pump system (SAGCHPS) has been built. Besides using a built-in vertical ground heat exchanger (VGHE) module in TRNSYS, the model also uses a newly developed VGHE module which considers coupled heat and moisture transfer in ground with variable soil properties...
Article
A comprehensive monitoring system has been implemented at the Archetype Sustainable Twin Houses at Kortright Center in Vaughan, Ontario, Canada to investigate the thermal performance of a variety of sustainable housing technologies. Among these technologies include a variable capacity twostage air-source heat pump (ASHP) system for residential spac...
Conference Paper
A comprehensive monitoring system has been implemented in the Archetype Sustainable Twin Houses at Kortright Center in Vaughan, Ontario, Canada to investigate the thermal performance of a variety of sustainable housing technologies. Among these technologies includes a two-stage variable capacity air source heat pump (ASHP) system in House A of the...
Article
Full-text available
Phase change materials (PCMs) can be implemented into building practice to enhance thermal storage performance, reduce indoor temperature fluctuations and improve the thermal comfort of occupants. As building energy simulation is taking an ever larger role in the design and analysis of energy efficient buildings, it is important to understand the c...
Article
The objective of this paper is to simulate the performance of a Solar Domestic Hot Water system and to investigate the contributions of different components in lowering the annual electricity demand for domestic hot water production. The system is for one of the Archetype Houses located at the Kortright Centre in Vaughan, Ontario. Simulation result...
Article
Full-text available
Phase change materials (PCMs) can be implemented into building practice to enhance thermal storage performance, reduce indoor temperature fluctuations and improve the thermal comfort of occupants. As building energy simulation is taking an ever larger role in the design and analysis of energy efficient buildings, it is important to understand the c...
Article
A comprehensive thermal conductivity (λ) database of three dry standard sands (Ottawa C-109, Ottawa C-190, and Toyoura) was developed using a transient line heat source technique. The database contains λ data representing a variety of soil compactions and temperatures (T) ranging from 25°C to 70°C. The tested standard sands, due to their repeatable...
Article
Computer simulation and analysis of a ground source heat pump system with horizontal ground heat exchangers operating in heating (max 5.5kW) and cooling (max 3.3kW) mode was carried out for a typical residential house, with 200m2 of living space, located in Sapporo (Japan). In spite of high electricity rate, the ground source heat pump system is mo...
Article
Accurate predictions of soil thermal conductivity k are strongly influenced by the volumetric fraction of quartz, Θq, data for which are very scarce. This paper reveals a new approach to estimate Θq from measured k records. First, an equation that relates the normalised k of soil (Ke) to the degree of saturation Sr is fitted to experimental k data,...
Article
This document presents a study for examining the viability of hybrid ground source heat pump (GSHP) systems that use solar thermal collectors as the supplemental component in heating dominated buildings. Loads for an actual house in the City of Milton near Toronto were estimated. TRNSYS, a system simulation software tool, was used to model the year...
Article
Full-text available
The natural convective velocity field in an enclosed air-filled cubical cavity with two opposing isothermal faces and the remaining four sides having a well-defined linear temperature rise from the cold to the hot face has been measured at different physical orientations and Rayleigh (Ra) numbers. In particular, two components of the velocity at th...
Article
An extension to a previously published work, this paper defines a new “diamond” orientation for the cubical-cavity benchmark problem in natural convection, and it presents new measurements on this as well as on a previously-treated orientation. Thus, measured were the average Nusselt number for an air-filled cubical cavity with two opposing isother...
Article
A simple ‘inter-particle contact heat transfer’ model for predicting effective thermal conductivity of soils at moderate temperatures (0–30°C) has been extended up to 90°C. The extended model accounts for latent heat transport by water vapour diffusion in soil air above the permanent wilting point; below that point, the soil thermal conductivity is...
Article
Heat transfer due to natural convection inside a closed cavity must be modeled to include the effects of turbulence if the Rayleigh number is sufficiently large. This study assesses the performance of several commonly used numerical turbulence models such as k-?, Renormalized Group k-? and Reynolds stress model, in predicting heat transfer due to n...
Article
An extension to a previously published work, this paper defines a new ''diamond'' orientation for the cubical-cavity benchmark problem in natural convection, and it presents new measurements on this as well as on a previously-treated orientation. Thus, measured were the average Nusselt number for an air-filled cubical cavity with two opposing iso-t...
Article
An inter-particle contact heat transfer model for evaluating soil thermal conductivity is analysed with respect to soils, representing different textural classes, exposed to moderate temperatures ranging from 15 to 30°C. This model is a combination of a self-consistent approximation model, enhanced with an inter-particle contact heat transfer corre...
Article
This paper describes the development of the Kersten function (Ke), which depends on soil temperature and the degree of saturation. The new Kersten function enables the prediction of thermal conductivities of moist soils also including high temperatures. The eight soils used in this paper represent three distinct textural groups, each having a compa...
Article
An analysis of soil thermal conductivity data shows that, at very low moisture content, this property first varies insignificantly and then begins to increase from a certain critical moisture content, whose value tends to depend on clay mass fraction. Two simple models evaluating the critical moisture content were developed; the first one is a frac...
Conference Paper
Prediction of soil thermal conductivity k is particularly difficult at high temperatures T (50-90°C) and very low moisture content θ; the k value may increase with temperature by a factor of 3-5. This phenomenon is due to water vapor migration resulting in latent heat transfer, which is strongly dependent on soil water characteristics (SWC). In the...
Article
Three different soils (sand, silty loam and silty clay) with five different degrees of saturation (0, 12.5, 25, 50 and 100%) were used in computer simulations. The performance of a ground heat pump system was found to depend strongly on the moisture content and the soil type (mineralogical composition). Alteration of soil moisture content from comp...
Article
Three different soils (sand, silty loam and silty clay) with five different degrees of saturation (0, 12.5, 25, 50 and 100%) were used in computer simulations. The performance of a ground heat pump system was found to depend strongly on the moisture content and the soil type (mineralogical composition). Alteration of soil moisture content from comp...
Article
This paper presents a new computerized procedure for dealing with the design of horizontal ground heat exchangers (HGHE). The computer program is based on the transient model of coupled nonlinear partial differential equations governing heat and mass flow in soils. The model is two-dimensional and delineates the operation of ground heat storage wit...

Citations

... In recent years, the GHE development and technology have been used in modern countries, particularly in Europe, due to its ability to provide cooling and heating during the summer and winter [13]. GHE is a promising application for cooling and heating spaces [14][15][16]. A blower is used to force air from the surrounding environment through pipes that are buried in the GHE. ...
... Unfortunately, the literature on this topic [9][10][11] does not directly reveal that, given that the Maxwell-Eucken model is typically not considered in such evaluation studies. This can probably be led back to the fact that the well-known De Vries model for effective soil thermal conductivity is already a further development of the Maxwell-Eucken model [16]. And previous studies have amply confirmed that this De Vries model is not the best contender in relation to effective soil thermal conductivity prediction [9][10][11], which is therefore a fortiori valid for the Maxwell-Eucken model. ...
... Soil thermal conductivity (λ) is a key thermal property used in a range of energy calculations in geotechnical and agri-environmental applications (Kojima et al., 2021;Zhao et al., 2019) as well as the most important property in studying soil thermal conditions (Tarnawski et al., 2020). It influences the soil thermal regime and can be used as an indicator of soil processes, such as microbial organic content (Taghizadeh-Toosi et al., 2019), air-filled porosity (Usowicz et al., 2006), soil bulk density (Mahdavi et al., 2016), soil water content (Romio et al., 2019), soil texture (Nikoosokhan et al., 2016), soil temperature (Morris et al., 2010), soil structure, and soil mineralogy (Schjønning, 2021). ...
... Taking an example of a geothermal lowtemperature ORC which nearly operates in the same temperature range, such as 80-100°C, the thermal efficiency with an organic fluid of R123 is 11.1% and exergy efficiency of 54.1%, as cited in the research article by Zhang et al. [7]. Leong and Mudasar [8] did a study on power generation from BTES with the aid of a simple ORC taking the DLSC system as a base model for the analysis. Firstly, they found the possibility of integrating the ORC with BTES, and secondly, when source temperature was above 67°C, the CHP system provided enough power to operate all the pumps of BTES and district loops. ...
... Therefore, the tube materials also play an important role in the comprehensive performance of the GHE, which should have durability, long lifespan, flexibility, and high thermal conductivity (Darkwa et al., 2013). The ground tubes in the GHE are made of polyvinyl chloride (PVC) (Agrawal, K.K. et al., 2019a;Zhao et al., 2016), polyethylene (PE) (Boughanmi et al., 2017;Brunetti et al., 2017;Cao et al., 2017;Dehghan B, 2018;Ren et al., 2018), steel (Cao et al., 2017;Ren et al., 2018), copper Wan et al., 2017), polyamide (PA) (Hantsch and Gross, 2013), plastic (Huchtemann and Müller, 2014;Lyu et al., 2020), polyurethane (PU) (Yang et al., 2016) and polybutylene (PB) (Lee et al., 2015;Yoon et al., 2021), in which the PE tube is the most common in the GHEs (60%), then steel (14%) and PVC (8%), respectively (Javadi et al., 2019c). ...
... However, it is worth noting that greenhouses usually adopt some economical cooling methods such as sunshade, ventilation, wet curtain, etc., instead of running the GSHP cooling mode [20], which might lead to serious soil thermal imbalance in the soil of well-group area when the heating system operates for a long time. The decrease of soil temperature will lead to the deterioration of energy efficiency of GSHP year by year, and even the risk of shutdown [21,22]. Li et al. [23] carried out a heating experiment with the GSHP for a greenhouse in northern Hokkaido, Japan. ...
... A conventional electric water heater worked as a booster element for the air-to-water heat pump system when outdoor temperature is out of the operating boundary. Substituting the low-efficient electric water heaters with a heat pump hot water system tends to further reduce energy usage costs in PH buildings [45,46]. The new unit is assumed to have the same seasonal COP (2.4) with the current one. ...
... They concluded that it is necessary to conduct a pre-design analysis to determine optimal system parameters that will ensure minimum energy consumption and favorable costs with the help of GSHP simulation models. Reliable numerical models and methods were shown in various studies [10][11][12]. ...
... On the other hand, in colder places (such as Canada), the temperature of the outdoor air is well below the freezing temperature for several months of a year. If ASHPWH system is installed in an unconditioned garage/porch or outside of the house, it undergoes a considerable drop in the thermal output during harsh winter months and will face a challenge to maintain the water temperature in the storage tank at or above 55 °C to prevent the possibility of Legionella bacteria [3][4]. Alternatively, if the ASHPWH is placed inside the house, which seems a more practical option in these conditions, the presence of ASHPWH might have an effect on the heating and cooling loads of the house. ...
... Ju et al. (2011) tested continuous and discontinuous thermal conductivity in the laboratory and discussed the influence of volumetric water content on thermal conductivity. Tarnawski and his team researched thermal conductivity characteristics of volcanic soils and pyroclastic soils (McCombie et al. 2016;Tarnawski et al. 2019). ...