Harjit Singh

Brunel University London · Department of Mechanical Engineering

The most appropriate Low Concentrating Photovoltaic (LCPV) technology suitable for European buildings located in mid-high latitudes under both maritime and continental climatic conditions has been identified as the Asymmetric Compound Parabolic Concentrator (ACPC). To date there is no published experimental data at different latitudes on the long-t...

Vacuum Insulation Panels (VIPs), despite being the best performing thermal insulation, face the challenges of high cost and environmental concerns associated with the core material, which typically consists of fumed silica (FS) or glass fibres. This study experimentally assessed the suitability of two novel core materials, which were generated from...

The present study introduces the first coupled model of the finite element method and Mie theory that predicts the heat transfer mechanism inside the expanded perlite vacuum insulation panels at a temperature range of 300-800 K. The finite element method is applied to discretise the governing equation of the steady state heat transfer and the three...

High-specification nanofluids can potentially enable cost-effective and highly efficient solar-to-thermal energy conversion. However, their implementation is adversely affected by poor absorption spectral range and stability challenges of the nanoparticles. Here we demonstrate the synthesis, full characterization and application of Cu-oxide nanopar...

Research into solar absorption chillers despite their environmental benefits has been limited to date to mainly larger systems whilst ignoring smaller building-scale units, which can significantly benefit from the use of optimally designed, low concentrating, non-imaging optical reflectors. A solar absorption chiller system designed to provide year...

The temperature of molten salts in the thermal energy storage tanks has strict bounds. A drop in temperature could cause local crystallization of the salt, while the maximum temperature is limited by the excess energy available through the concentrated solar power plant. In the work discussed in this chapter, a system-level (thermal energy storage...

For solar thermal applications, a novel idea is to employ directly radiation-absorbing working fluids to completely replace metallic receiver tubes. Advances in nanotechnology have enabled development of nanofluids, an optimized mix of nanoparticles (NPs) and a base fluid, which can absorb a large proportion of the solar spectrum. A nanofluid compr...

Directly absorbing nanofluid-based solar thermal collectors are being proposed for heating and cooling of residential and industrial buildings. In these solar thermal collectors (STCs), nanoparticles absorb the incident radiation, convert it into heat and finally transfer to the working fluid in full volume. The performance of these collectors depe...

This chapter describes the installation method of vacuum insulation panels (VIPs) externally on a demonstration wall in an operational residential building in the United Kingdom. The study assesses the effectiveness the VIPs in terms of the heat loss through the walls using temperature profiles measured in the demonstration application. The analysi...

The core material contributes ≥40% of the total cost of a fumed silica based vacuum insulation panel (VIP). Expanded perlites, which come at approximately one-tenth of the current price of fumed silica, have been identified as potential core material candidates. Though, the characteristic vacuum insulation properties i.e. evacuated thermal conducti...

Directly solar radiation absorbing nanofluids have the potential to absorb a wide spectrum of solar radiation and displace selectively coated metallic receivers in solar thermal collectors. Parameters including nanoparticle concentration, synthesis and storage conditions, can influence their long-term usage. In this study, 60 minutes was found to b...

Low concentrating photovoltaic (LCPV) systems offer viable solution for generating higher energy output per unit cell area compared to a typical flat PV panel, making them potential candidates for building retrofit. However, the best LCPV geometry for a given location is yet to be identified. The current study investigates the technical, economic a...

A solar concentrator of the type V-Trough is designed for a multipurpose integrated solar energy project in Helwan of Egypt. A suitable place in the NRIAG is selected. A concentration ratio matching the stability of the unconventional cooling technique for PV module 2.3 is chosen. A new cooling system with heat pipes for the module is manufactured....

Anaerobic digestion has been widely accepted for energy and resource recovery from biomass residues. However, the produced biogas from the process mainly composed of methane and carbon dioxide is lower in calorific content, which is a major drawback for its direct application as an energy fuel. Therefore, different biogas upgradation systems based...

Directly solar radiation absorbing nanofluids can displace selectively coated metallic receivers in solar thermal collectors. Current challenges include settling and instability when stored for longer durations or at higher temperatures. In this study, we report key optical properties and stability limits of nanofluids containing amorphous-carbon n...

The temperature of molten salts in the thermal energy storage tanks has strict bounds. A drop in temperature could cause local crystallization of the salt, while the maximum temperature is limited by the excess energy available through the concentrated solar power plant. In the present work, a system level (thermal energy storage tank) computer mod...

For solar thermal applications, a novel idea is to employ directly radiation-absorbing working fluids to completely replace metallic receiver tubes. Advances in nanotechnology has enabled development of nanofluids, an optimized mix of nanoparticles (NPs) and a base fluid, which can absorb a large proportion of the solar spectrum. A nanofluid compri...

In this study, 1-year real life performance of a 30kWp rooftop solar PV power plant installed at the Köprübaşı Vocational School of the Manisa Celal Bayar University was evaluated and is presented here. The PV plant is comprised of 116 polycrystalline modules mounted 15 cm proud of the roof surface providing a gap between roof surface and the botto...

Through the ReCO2ST project, vacuum insulation panels have been installed on the demonstration building at Brunel University London and are being monitored for thermophysical performance. First results show monthly average temperatures in the range of 12.8 °C – 15.8 °C between the wall and the insulation layer when monthly average ambient temperatu...

Low concentrating photovoltaic technologies (LCPV) for building application offer viable solutions in improving the conversion efficiency of solar cells leading to an improved electrical output per unit cell area required when compared to conventional solar photovoltaic modules. The current study explores the feasibility of different geometrically...

Transmission is the major contributor (> 50%) to the total cooling load for typical domestic refrigerators. Understandably, insulation in refrigerator walls plays an important role in reducing it. In the present work, a system level computer model of domestic refrigerator has been developed and the effect of different insulation materials, with var...

Rapid plasma-induced non-equilibrium electrochemistry (PiNE) at atmospheric pressure was used to prepare surfactant-free gold nanoparticles and copper oxide quantum dots. A suite of chemical and physical char-acterisation is carried out to assess the as-prepared materials. Nanofluids comprised of these nanoparticles in ethylene glycol have been pre...

This paper reports the results of the experimental study conducted on the charging and discharging performance of a pentaerythritol (PE) blended with the low melt alloy (LMA) of Bi-Sn-In-Zn. The charging and discharging time, power, the efficiency of PE added with 0.5, and 1.0 wt.% of LMA determined using a shell and tube type thermal energy storag...

Globally, the electrical energy consumption of domestic refrigerators is approximately 6% of the total consumed. Typically, refrigerators are insulated with materials, such as foams (thermal conductivity >20 mWm⁻¹K⁻¹). Alternatively, using Vacuum Insulation Panels (VIPs) (thermal conductivity < 7 mWm⁻¹K⁻¹) would significantly reduce their overall e...

Fish is a highly perishable food as it loses quality because of bacterial or enzymatic activity or both with time. The present paper describes a computer model of a fish box, refrigerated with flake ice, developed to study the effect of parameters like fish to ice ratio and box usage time (the time for which the fish remains fresh inside the box) a...

This study presents an alternative core material developed by using waste sawdust powder for eco-friendly Vacuum Insulation Panels (VIPs). This alternative VIP core material was prepared by using locally sourced waste sawdust powder from woodwork industry. Three samples containing varying mass ratios of sawdust and fumed silica were characterized i...

Nanofluids inherently have high emissivity in the mid-infrared region making them unsuitable for satisfying the conditions of solar selectivity required for direct absorbers. In this study, a layer of silicone oil is located above nanofluid comprising of graphite nanoparticles and deionized water. Silicone oil layer is shown to act as a barrier aga...

In 2017, 11.41 million refrigerators and 1.85 million freezers were sold in USA alone; each unit consuming approximately 500 kWh/year with an average life expectancy of 12 years. Traditionally, fridges and freezers have been insulated with polyurethane foam (thermal conductivity >0.020 W/m.K). There is a significant scope of reducing the heat gain...

This paper presents systematic design procedure and features of a sun simulator developed for testing low concentrating linearly focusing solar photovoltaic concentrators. The designed solar simulator comprises of a xenon short arc lamp and paraboloidal reflector for uniform radiative flux distribution on focal plane at desired radiation intensity....

This paper reports the design and construction of a modified active solar distillation system (MSDS) and comparison of its performance parameters with that of a conventional solar still (CSS). MSDS consists of a solar still, a Fresnel lens concentrator with an evacuated receiver tube and a serpentine loop type heat exchanger. Al 2 O 3-Therminol-55...

Geometrically equivalent V-trough and compound parabolic concentrators (CPC) were simulated to characterise the variation in optical efficiency using ray tracing modelling with COMSOL Multiphysics. The effect of CPC truncation and V-trough side wall angles were studied. The truncated CPC demonstrated much improved light acceptance outside the desig...

In 2017, 11.41 million refrigerators and 1.85 million freezers were sold in USA alone; each unit consuming approximately 500 kWh/year with an average life expectancy of 12 years. Traditionally, fridges and freezers have been insulated with polyurethane foam (thermal conductivity >0.020 W/m.K). There is a significant scope of reducing the heat gain...

This paper presents systematic design procedure and features of a sun simulator developed for testing low concentrating linearly focusing solar photovoltaic concentrators. The designed solar simulator comprises of a xenon short arc lamp and paraboloidal reflector for uniform radiative flux distribution on focal plane at desired radiation intensity....

Solar collectors that can directly absorb radiation represent an emerging realm of solar thermal systems wherein the collection as well its subsequent conversion to the useful thermal energy happens within the working fluid. Nanofluids (stable dispersions of nanoparticles in the basefluid) have been found to be promising working fluids for realizin...

Solar thermal systems are one of the renewable energy systems used in the residential buildings for the heating purpose, and with these systems, the usage of non-renewable energy resources decreases. To improve the performance of solar collectors, engineers and scientists are regularly working on it. Direct absorption-based solar thermal collectors...

Development of VIPs using low cost core materials and their thermo-physical characterisation.

Nanofluids that directly absorb solar radiation have been proposed as an alternative to selectively coated metallic receivers in solar thermal collectors. Given the expense of characterising a potential nanofluid experimentally methods for comparing nanofluids virtually are needed. This paper develops a computational wave optics model using COMSOL...

The thermo-physical behavior of Myo-Inositol (MI), (a sugar alcohol), was investigated as a potential material for developing more compact solar thermal energy storage systems than those currently available. This latent heat storage medium could be utilized for commercial and industrial applications using solar thermal energy storage in the tempera...

This paper reports experimentally measured thermal and optical properties of Al 2 O 3-Therminol Ò 55 nano heat transfer fluid (nHTF) in conjunction with a specially developed line focusing Fresnel lens based solar thermal concentrator. Solar collector tests were conducted under real life outdoor ambient and solar radiation conditions. A range of vo...

Solar photovoltaic conversion systems with integrated, low concentration ratio, non-imaging reflective concentrators, could be on south facing building roofs used to generate power at a lower cost than currently available proprietary systems. The experimental investigation presented by this research provides information on the optical and energy co...

In 2011, UK’s low temperature heat (<500 °C) demand accounted for 41% of total industrial heat demand, which resulted into 70% of greenhouse gas emissions from the sector. India’s low temperature (80-250 °C) industrial heat demand accounted for 31% of its total energy consumption in 2006-2007. Theoretically concentrating solar thermal technologies...

We report the development of an optimised vacuum panel insulated vaccine storage chamber intended for storing vaccines at 4 ˚C - 8 ˚C for up to 30 days without any active means of cooling. The vaccine chamber performance relies on an innovative arrangement of an ice container and vacuum insulation panels (VIPs) in conjunction with Sure Chill’s pate...

A numerical investigation of the performance of a multi paned smart window integrated with water-cooled high efficiency third generation GaAsP/InGaAs QWSC (∼32% efficiency) solar cells illuminated by two-axis tracking solar concentrators at 500× in the inter pane space is presented. Optimising system parameters such as optical concentration ratio a...

The thermo-physical properties of expanded perlite-fumed silica composites were experimentally investigated as an alternative lower cost material for vacuum insulation panel (VIP) core using expanded perlite as a cheaper substitute of fumed silica. Pore size analysis was carried out using nitrogen sorption technique, mercury intrusion porosimetry a...

A MATLAB-based computer model to design a novel directly absorbing receiver system (DARS) for concentrating solar collectors employing nanofluid-based solar radiation volumetric absorption is presented. Graphene and aluminum nanosphere-based suspensions in Therminol VP-1 were simulated to identify the optimum thermo-geometric configuration of a DAR...

Two solar photovoltaic-thermal (PVT) energy conversion systems are described and their performance tested under laboratory conditions. One of these was a simple Flat Plate (FP-PVT) design, with headers and risers for heat removal the other a fixed linear axis Compound Parabolic Concentrating solar PVT (CPC-PVT) energy conversion system with a heat-...

A detailed experimental study was undertaken to analyse the natural convective heat transfer in CPC cavities, a complex function of collector orientation, geometrical aspect ratios and thermal boundary conditions at the enclosure walls. Results are reported for CPC solar collectors with full-, three quarter- and half-height reflectors, CR = 2 and a...

Two solar photovoltaic-thermal (PVT) energy conversion systems are described and their performance tested under laboratory conditions. One of these was a simple Flat Plate (FP-PVT) design, with headers and risers for heat re- moval the other a fixed linear axis Compound Parabolic Concentrating solar PVT (CPC-PVT) energy conversion system with a hea...

A set of technological interventions has been identified which are suitable for applications in the majority of existing UK dwellings and which would significantly reduce their carbon footprint. The dwelling types are semi-detached, detached and terraced. The paper considers two scenarios, viz. i) using present-best technologies and ii) looking at...

Dispersing trace amounts of nanoparticles into common base-fluids has a significant impact on the optical as well as thermophysical properties of the base-fluid. This characteristic can be utilized to effectively capture and transport solar radiation. Enhancement of the solar irradiance absorption capacity leads to a higher heat transfer rate resul...

Dispersing trace amounts of nanoparticles into the base-fluid has significant impact on the optical as well as thermo-physical properties of the base-fluid. This characteristic can be utilized in effectively capturing as well as transporting the solar radiant energy. Enhancement of the solar irradiance absorption capacity of the base fluid scales u...

This paper makes an attempt to analyze heat transfer aspects of a nanofluid based linear parabolic solar collector. A detailed one dimensional transient heat transfer analysis involving coupled conduction-radiation heat transfer in absorbing, scattering and emitting media has been carried out. Further, radiative and convective heat losses as a func...

Demand for energy efficient buildings has increased drastically in recent years and this trend will continue in the future. Insulating building elements will play a key role in meeting this demand by reducing heat losses through the building fabric. Due to their higher thermal resistance, Vacuum Insulation Panels (VIPs) would be a more energy effic...

Natural convective heat transfer in cavities is a complex function of cavity shape, aspect ratio, boundary conditions at the walls and the properties of the fluid contained within the enclosure. Considerable research into natural convection in regular shaped cavities, such as those of rectangular, square cross-section, or cylindrical annuli has bee...

Enhancement of energy efficiency and introduction of newer and more efficient space and water heating technologies in the UK domestic sector are essential if the UK is to achieve its ambitious target for 2050 of reducing greenhouse gas (GHG) emissions to less than 80% of 1990 levels. The UK domestic sector currently relies heavily on conventional b...

For northern maritime climates with a high diffuse component of solar radiation, non-imaging CPC solar collectors with concentration ratios of up to 2 can be used to concentrate direct as well as diffuse incident solar radiation without tracking. Due to the concentrated solar flux incident on the absorber, these systems can produce temperatures in...

Previous work by the authors has shown the effect that changing climate and small power/lighting equipment can have on heating and cooling loads of typical existing UK offices, for a 2005 baseline. This follow-on study uses an improved office, with reduced cooling loads, and performs retrofit fabric and HVAC measures to further reduce the energy an...

An energy simulation package, Environmental Systems Performance-research (ESP-r) was used to predict the energy performance of selected building variants, which consist of one typical UK school, two three-storey estate agent and small offices, two single-storey convenience stores and fifty double-storey semi-detached dwellings. Building models were...